Forum:Deck Guide/A Legendary Ocean

by Gadjiltron

Intro

Out of the first 10 non-character Structure Decks released, it is pretty much agreed that Structure Deck 4: Fury from the Deep was one of the best on its own. Why? One Field Card was behind it all: A Legendary Ocean (ALO for short). With its effects, it allowed WATER Decks to become competent, though not exactly competitive. As Konami moves on to release Abyss Rising which lends more support to WATER Decks in general, ALO Decks get more monsters and cards to experiment with.

Related Guides

A number of Deck Types are capable of harnessing the power of A Legendary Ocean, though not as effectively as those centered around it. Please refer to the corresponding Guide (if available) where necessary:

• Fish Decks
• Frog Decks
• Ice Barrier Decks
• Ice Counter Decks
• Mermail Decks
• Penguin Decks

Mechanics

As the name indicates, the ALO Deck is based off its namesake Field card. Said Field is capable of giving an ATK and DEF boost, a Level modification, while also activating certain effects that make several monsters much more deadly. More details on the card below.

While there exist several similar Field cards that also benefit WATER Decks, this Guide only covers Decks that are built around ALO's unique effects.

Analysis

Strengths

• Variety - There are many options available to the ALO Deck, ranging from beatdown to one-sided locking to field-nuking.
• Search and recycle power - Quite a number of key cards in the ALO Deck can be easily searched or recycled by the cards they often use. The fact that newer WATER support released doesn't specify archetypes helps, since they can also be splashed into the Deck if necessary.

Weaknesses

• Dependent on field - A number of monsters used by the ALO Deck require its presence to be at their full potential. However, unlike Gravekeeper's Decks, ALO Decks are still capable of holding their own without the field.
• Not enough space - There are plenty of great cards at a player's disposal. But it's also impossible to run them all at once. Simply writing on paper is not enough to work out the problems with using a certain card over another.

The Basics

Before we get started on what usually appears in the Deck, first we look at its central card.

• A Legendary Ocean - Three effects, so let's go through these one by one.

1. ALO has its name treated as "Umi". This allows many WATER cards' effects to trigger because they depend on Umi being on the field. While this means that you can't run ALO aside the original Umi or other duplicates, ALO is practically an upgraded version of Umi due to its following two effects.
2. WATER monsters in both players' hands and fields have their levels lowered by 1. This is often central to the strategies played by ALO Decks because it can allow otherwise mediocre LV5 monsters to be summoned without Tribute, or let LV4 monsters slip under locking cards like Gravity Bind and Level Limit - Area B.
3. All WATER monsters gain 200 ATK and DEF. Doesn't seem like much, but compared to the original Umi which was picky over which Monster Types got the bonus, a blanket bonus to a single Attribute was more welcome.

Now, the cards that are common across most ALO Decks:

• Warrior of Atlantis - Introduced in FOTB along with other field searchers, Warrior of Atlantis stands at an already decent 1900/1200 without ALO. The player can discard him to the Graveyard to fetch ALO from the Deck, turning him into a LV3 2100 beater. Definitely a must in all Decks.
• Nightmare Penguin - With base stats of 900/1800, you'd rather be Setting him to use his good DEF. Actually, he likes it if you Set him - if he gets flipped up, you get to bounce a card the opponent controls. And as an added bonus, while face-up on the field, all your WATER monsters (including himself) gain a further 200 ATK bonus, making your beaters even bigger. And once you cross 2000 ATK, every small ATK bonus counts.
• Armed Sea Hunter - With stats of 1800/400, Armed Sea Hunter is a very good beatstick hailing from the usually underlooked ANPR. His effect makes him shine in a WATER Deck, because if there's another WATER monster on his side of the field, Sea Hunter negates the effects of anything he battles with after damage calculation. Note that this is capable of shutting off Continuous effects and anything that resolves outside the field. His second effect allows you to destroy a LV3 or lower WATER monster in his place if anything attempts to destroy him. In an ALO Deck, that means almost everything you have can bite the bullet for him.
• Mother Grizzly - A classic searcher for WATER monsters. When destroyed in battle, she can Special Summon any WATER monster from your Deck with base 1500 ATK or less. The valid targets available, however, will differ based on what variation you'll be running.
• Levia-Dragon - Daedalus - The ace card of any ALO Deck. While it looks rather cumbersome being a LV7 monster, ALO downgrades it to LV6, turning this leviathan into a one-Tribute 2800 ATK. Then we get to its effect, where it can send Umi (or a duplicate) to the Graveyard to destroy everything else on the field. If Judgment Dragon taught us anything, it's that this sort of effect is worth trembling over.
• Codarus - This mini-Daedalus isn't as powerful as the original, but at the very least it can be searched and doesn't need at least one Tribute. His effect is watered down yet buffed in different ways. In exchange for Umi, he sends 2 cards on the field to the Graveyard, allowing him to circumvent destruction negators like Stardust Dragon.
• Mermaid Knight - 1500 ATK is right at the upper bound of searchability. With Umi out, Mermaid Knight gains the ability to attack twice per Battle Phase. Double attacks are always welcome, especially when combined with an ATK boost.
• Abyss Soldier - Another decent beatstick with 1800/1300 base stats. Abyss Soldier can discard a WATER monster to bounce any kind of card on the field. This somewhat strict cost hampers its ability, but it's good for removing monsters too big for yours to handle.
• Number 17: Leviathan Dragon - While ALO's LV-decreasing effect interferes with Synchro Summons, it still keeps the option of playing Xyz Monsters available. Leviathan Dragon fits in nicely because most of the LV4 monsters played drop to LV3, opening up the option of using it as an emergency beatstick, and it still gets effects from WATER support.
• Black Ray Lancer - Okay, it's a bit odd because, unlike its appearance suggests, it's a DARK Beast-Warrior. Nevertheless, it specifies 2 LV3 WATER monsters as its summon requirement, which the Deck can easily fulfill. Black Ray Lancer can detach an Xyz Material to negate one face-up monster's effects until the End Phase. While it's only temporary unlike Armed Sea Hunter's, at least Lancer doesn't need another monster to be present for negations and does not need to attack (and risk setting off Mirror Force or the like) before negating the effect.
• Salvage - Allows you to pick exactly 2 WATER monsters, each with 1500 ATK or less, from your Graveyard and return them to your hand. It's great if you're refueling your hand for Abyss Soldier's effect, or to simply reuse things like Nightmare Penguin.
• Spiritual Water Art - Aoi - A handy chainable Trap that, at the cost of Tributing a WATER monster, lets you see the opponent's hand and send a card among it to the Graveyard. Great for letting your WATER monsters evade worse fates like getting banished or topdecked, or to retaliate against attempted mass removal.
• Aegis of the Ocean Dragon Lord - This Trap protects all of your LV3 or lower WATER monsters from being destroyed by any means. With ALO out, that means almost all your monsters are viable candidates for its effect. Not bad!
• Aquamirror Cycle - Hailing from GAOV, Aquamirror's art implies that you'd be using it for Gishki, but it works just as well for any WATER Deck. First, you target a WATER monster you control and two WATER monsters in your Graveyard. If the card's effect is not negated, the WATER monster on your field gets shuffled into your Deck, while the monsters in your Graveyard are returned to your hand. While it's not exactly the best way of dodging removal, at the very least this card isn't restricted by the targets' ATK, unlike Salvage, and can recycle your bigger monsters.

Variants

Not So Cumbersome

This beatdown variant uses ALO to cut LV5 monsters down to LV4, creating no-Tribute monsters going up to a monstrous 2650 ATK. Cards usually found in this variant include:

• Giga Gagagigo - Everyone's favourite tonguetwister lizard makes for the biggest possible non-Tribute monster which the Deck can accomodate. With ALO he turns into a LV4 2650 ATK behemoth. Brutal.
• The Legendary Fisherman - Alright, 1850 ATK isn't very good on a LV5 monster, but at least ALO eliminates his need for a Tribute. With ALO, Fisherman becomes unattackable and immune to Spells. This means that he doesn't receive a stat buff from ALO, but he can create an irritating wall if left alone.
  • Side Note: I recall there being a time where Fisherman's odd rulings let the opponent attack you directly if he's the only monster you control. I'm pretty sure the new problem-solving card text should rectify this behaviour.
• Cyber Shark - A pseudo-Cyber Dragon where you can Normal Summon it without Tribute while you control a WATER monster. Slightly more flexible than the other LV5s in the Deck in that it still can function without ALO's presence.
• Shark Cruiser - What makes worth playing is its effect. When destroyed by an opponent's card effect, you get to Special Summon 2 LV4 or lower WATER monsters from your Deck. No ATK restrictions. If it actually goes off, you can replace it with, say, 2 Armed Sea Hunters for effect-negating fun.
• Mechanical Sea Dragon - Plesion - A LV5 WATER monster hailing from ABYR with somewhat lackluster stats of 2300/1800. If you control a Sea Serpent, it can be Normal Summoned without Tribute... but then again, if you have ALO, you can do that anyway. Once per turn, you can Tribute a WATER monster you control (yes, including itself) to destroy a face-up card your opponent controls, letting you pick off bigger threats or defuse troublesome S/Ts.
• Numen erat Testudo - 1800/0 for LV5 is universally agreed to be horrible, but NeT prevents either player from Special Summoning monsters with more than 1800 ATK, preventing the opponent from bringing out most Extra Deck monsters. As for you, you're largely unimpeded by its effects.
• Hydrogeddon - This member in the forgettable Chemical archetype is a good LV4 all-rounder at 1600/1000, but if it scores a kill, it Special Summons a copy of itself from the Deck, letting you keep the offensive pressure.
• Moray of Greed - Nothing's worse than getting a hand full of LV5 monsters when you don't have ALO out yet. Shuffle two of them in and draw 3 cards, and hopefully you get something better.

Deep Pressure

This lock variant uses ALO to drop the levels of your monsters by 1, allowing your otherwise LV4 monsters to slide under Gravity Bind and Level Limit - Area B while your opponent is denied that luxury. This variant tends to use:

• Amphibious Bugroth MK-3 - It is searchable with a base 1500 ATK and can attack directly with Umi on the field, so ALO turns it into a 1700 ATK direct attacker that slides under the lock. A major nuisance, in other words.
• Drill Barnacle - A direct attacker that's slightly different from MK-3. Instead of needing ALO to attack directly, it can do that on its own. It starts at a base 300 ATK but gains 1000 ATK each time it inflicts Battle Damage. Left unchecked, Drill Barnacle can suddenly grow to a massive size and have your opponent finished off in about 4 hits.
• Flip Flop Frog - A little monster that, once flipped up, bounces monsters equal to the number of Frogs you control, including itself. The better part is that it can flip back down so you can further annoy an opponent by bouncing their high-level monsters.
• Blizzard Dragon - A WATER monster with decent stats of 1800/1200, and each turn it can "freeze" an opponent's monster by rendering it unable to attack or change battle positions for the turn. Very helpful in a stall Deck.
• Gravity Bind and Level Limit - Area B - The main strategy of the lock, and allows you to buy time or whittle away at a helpless opponent. Note that with Xyz Monsters being available and utterly unrestricted by them, this strategy isn't as efficient.
• Eisbahn - On the other hand, this can work as an answer to the Xyz Monster's immunity to the lock. Any non-WATER monster that's Summoned can be changed to Defense Position, provided you control a face-up WATER monster first. With that lock in place, yeah, you probably do. Keep Xyz Monsters from attacking you while you bounce them off with Flip Flop Frog.

Sub-Type

Among WATER supports from the later boosters lie even more support that instead specify three kinds of monster Types: Aqua, Sea Serpent, and/or Fish. A majority of the monsters hailing from these three Types are WATER monsters and so work well with ALO.

While there exist other cards that belong to the Aqua/Sea Serpent/Fish Types, those aren't WATER-attributed and actually support a different strategy altogether. Please refer to the Fish guide for Decks that use them.

Decks specializing in these three Types tend to use:

• Spined Gillman - A LV3 Monster with base stats of 1300/0, but his effect buffs the ATK of all Aqua/Fish/Sea Serpents by 400. Effectively this makes him a decent 1700 beater on his own, and the total boost gets bigger as you add on ALO and Nightmare Penguin. Even Mermaid Knight's double attack ability becomes much more deadlier.
• Lost Blue Breaker - A LV3 Sea Serpent with average stats of 1400/0. If you control another Aqua/Fish/Sea Serpent, you can Tribute it to destroy a S/T on the field. LBB isn't too shabby for S/T removal, considering that most other cards can only bounce, but it's a pity that you don't get to keep it on the field.
• Atlantean Assaultman - Looking like a buffed version of the originally fail-tastic Atlantean Pikeman, Assaultman starts at a humble 1400/0 but quickly grows to 2200/0 as long as you control another Fish/Aqua/Sea Serpent. Combo with Gillman and Assaultman's ATK surges to an impressive 2600, allowing it to take down monsters up to double its Level!
• Deep Sea Diva - A Tuner which can Special Summon a LV3 or lower Sea Serpent from your Deck when Normal Summoned. Normally, people only use her to Special Summon another copy of herself to use for Synchro Summons, but she can search out Gillman, LBB, or Assaultman.
• Surface - Special Summons a LV3 or lower Fish/Aqua/Sea Serpent from your Graveyard. While your monsters don't manage to Level down from ALO while in the Graveyard, viable useful targets for Surface include Gillman, Assaultman and LBB.
• Aqua Jet - Target Fish/Aqua/Sea Serpent you control gains 1000 ATK until... wait, permanently? Nice! Monsters you want to keep on the field like Armed Sea Hunter or Spined Gillman are definitely excellent targets for this card. Even Mermaid Knight becomes a devastating beast with the ATK boost.
• Forgotten Temple of the Deep - This Continuous Trap only treats itself as Umi while face-up, so it doesn't clash with running 3 ALO in your Deck. This also allows you to use Codarus' effect without giving up your ALO. Forgotten Temple's other effect lets you banish a LV4 or lower Fish/Aqua/Sea Serpent on your field during either player's turn, only to have it return during your End Phase. This allows your monsters to dodge removal and the like, but unlike Interdimensional Matter Transporter they don't come back immediately at the turn's end.

Sea Trinity

Main Deck Monster Cards Nightmare Penguin x2 Warrior of Atlantis x3 Spined Gillman x3 Atlantean Assaultman x3 Mermaid Knight x2 Levia-Dragon - Daedalus x2 Armed Sea Hunter x3 Mother Grizzly x2 Spell Cards A Legendary Ocean x3 Salvage x2 Surface x2 Aqua Jet x2 Dark Hole Book of Moon Mystical Space Typhoon x2 Trap Cards Aegis of the Ocean Dragon Lord x2 Forgotten Temple of the Deep Mirror Force Torrential Tribute Bottomless Trap Hole Aquamirror Cycle Extra Deck Xyz Monsters Number 17: Leviathan Dragon Black Ray Lancer

Battleship Orca

A somewhat famous card that benefits greatly from ALO is Orca Mega-Fortress of Darkness and its two sorts of ammunition. It's more intended to be a fun Deck than anything competent. Cards include:

• Orca Mega-Fortress of Darkness - At a base LV5 for 2100 ATK, this basically needs ALO to become competent. It uses two kinds of monsters as ammunition to destroy opposing monsters or S/Ts, which will be elaborated below.
• Torpedo Fish and Cannonball Spear Shellfish - On their own, the ammo monsters are simple low-level 1000 ATK monsters that become immune to Spell Cards while Umi is on the field. Torpedo Fish can be Tributed by Orca to destroy a monster, while Shellfish destroys S/Ts instead.
• Salvage, Surface, and Aqua Jet - These cards tend to be spammed in this Deck more often to constantly reuse Orca's ammunition. Even with the ALO's boost, Orca's ATK is still subpar, so an Aqua Jet makes it competent in combat.

True Atlanteans

The new Structure Deck: Roar of the Sea Emperor is another WATER-based Structure Deck that deals with Sea Serpents. The catch is that a lot of its cards like it if its monsters are LV3 or lower. Many of the new Sea Serpents belong to the "Atlantean" archetype, but they also have secondary effects that encourage the player to run other WATER monsters alongside them. Let's take a look at what the Structure Deck introduces:

• Atlantean Dragon Poseidra - A new boss monster, it seems, that would rival Levia-Dragon. It's also LV7 but boasts a base 2800 ATK, making it a one-Tribute 3000 ATK monster with ALO. However, if you do that, it's effectively a Vanilla monster. What its effect requires looks rather cumbersome, because you need to Tribute 3 LV3 or lower WATER monsters to Special Summon it from your hand. For all that effort, you get a Giant Trunade effect, and if you bounced 3 or more cards, all your opponent's monsters permanently lose 300 ATK per card bounced. That's at least 900 ATK if you get the effect going, which is often enough to bring your opponent's monsters' ATK scores in reach of your own. Even with ALO's LV-decreasing effect allowing your stronger monsters to fulfill Poseidra's effect, often you'd rather want to keep your combination of monsters unless the opponent has a wide array of S/Ts that are worrying you. Three attacks are often better than one.
• Atlantean Dragon Riders - On the other hand, the other Atlantean monsters look better. Dragon Riders stands at a good 1800/0 for a LV4, putting it on par with Abyss Soldier and Armed Sea Hunter. His effect shines best when combined with ALO, since he lets all your LV3 or lower Sea Serpents attack the opponent directly. That means with ALO out he becomes a 2000 ATK direct attacker. Painful! That's not all. If sent to the Graveyard from anywhere as a cost for activating a WATER monster's effect (e.g. Abyss Soldier), you get to add any Sea Serpent (excluding Dragon Riders) from your Deck to your hand, resulting in no net loss in hand size. Oh, and that searching doesn't specify LV or stats, so feel free to search Daedalus or Poseidra. So strong was this search effect that it got Limited in the TCG as of sep 2013
• Atlantean Marksman - 1400/0 for LV3 is more or less average and keeps it searchable and recyclable, but that gives it a few problems when trying to trigger its effect. If it inflicts Battle Damage to the opponent, you get to Special Summon a LV4 or lower Atlantean monster (other than itself) from your Deck. It's definitely designed to combo with Dragon Riders since it'll be free to attack directly. With ALO out you can choose to bring out another Dragon Riders with this card's effect to continue the direct-attack spree! Like Dragon Riders, Marksman can destroy a Set card your opponent controls if sent to the Graveyard from anywhere to activate a WATER monster's effect.
• Atlantean Armed Soldier - By now, you'd have realized that Atlantean monsters all have 0 DEF. Armed Soldier reverses this trend, this time by sporting 0 ATK and having an okay 1600 DEF. This tempts you to Set him, but his effect allows you an extra Normal Summon of a LV4 or lower Sea Serpent from your hand each turn while he's face-up. On the other hand, you might want to keep him in your hand or something, because if he is sent to the Graveyard for the activation of a WATER monster's effect, you get to destroy a face-up card your opponent controls. After discarding him, feel free to use Surface to bring him back up in Defense Position in order to reap his extra Normal Summon and save a headache.
• Atlantean Roar - Target 3 LV3 or lower Sea Serpents in your Graveyard and Special Summon them. This looks like a perfect lead-up to Poseidon, only that you can't Special Summon other monsters in the same turn you activate this card. By this point, we should have covered a fair number of Sea Serpents with a base of LV3 or lower, all of them with the ability to mesh very well with each other. Either pop this card during the opponent's End Phase if you want to Summon Poseidra, or to summon a mix of Gillman and Assaultman for a fierce beatdown.

Other Tips

There's an enormous list of general WATER support, so don't be alarmed if you're having trouble deciding what to pick from, or trying to make space to use them. Several cards not mentioned above include:

• Ocean Dragon Lord - Neo-Daedalus - And advanced version of Daedalus, but is a Nomi and can only be summoned by Tributing the original Daedalus. Neo-Daedalus possesses an upgraded effect of Daedalus, being able to send off Umi to send every other card on the field and in both players' hands to the Graveyard, dodging little keywords like "destroy" and "discard" to make his effect harder to negate. While it means that Neo-Daedalus practically guarantees that your opponent will struggle in trying to turn the tables, its status as a Nomi makes players torn between choosing to play it or simply focusing on the original Daedalus.
• Mermail - Abysspike and Mermail - Abyssturge - These two cards technically belong to the Mermail archetype but they can affect any WATER monster if you so choose. Their effects can only activate once per turn, and copies don't count. When they're Normal or Special Summoned, you can discard a WATER monster from your hand to add a LV3 or lower WATER monster to your hand. Where from depends on the monster. Abysspike adds from the Deck, while Abyssturge adds from the Graveyard. Both these monsters' discarding effects are capable of triggering the new Atlantean monsters' effects, so give them a shot in an Atlantean Deck.
• Mermail - Abysslang - The cool part about Abysslang is that he protects other monsters from attacks while granting a nice 300 ATK boost to your other WATER monsters. The problem here is that he's unaffected by that boost, and is pretty frail at 1200 ATK.
• Ice Spirit God - Moulin Glace - An alternative boss monster for any WATER Deck. Moulin Glace is a Semi-Nomi that can only be Special Summoned while you have exactly 5 WATER monsters in your Graveyard. On Special Summon, Moulin Grace discards 2 random cards from your opponent's hand, disrupting their options for future plays. That's great and all, but against Dark World you're in for a world of pain if the wrong cards are hit. Then there's the problem of losing your next Battle Phase when it leaves the field in any way. One would rather stick to using Daedalus.
• Metallizing Parasite - Soltite and Metallizing Parasite - Lunatite - These two are bizarrely high-Leveled Union monsters that hardly do a thing on their own. Fortunately, they are searchable by Mother Grizzly, and if they end up in the hand ALO can relieve them of one Tribute requirement. Both parasites can Union onto any monster, and they protect from different things. Soltite protects from destruction and targeting by the opponent's monster effects, while Lunatite grants immunity to the opponent's Spells. Note that Soltite uses the improved Union monster ability where it can protect from destruction from any source once, rather than only destruction by battle.
• Abyss Warrior - A close cousin of Abyss Soldier hailing from the new ABYR pack. Rather than bouncing one card on the field, Abyss Warrior instead targes a monster in either player's Graveyard and returns that to the top or bottom of the Deck. Good for recycling your own monsters and breaking your opponent's Graveyard setup.
• Deep Sweeper - Somewhat similar to Lost Blue Breaker, Deep Sweeper can Tribute itself to destroy a S/T on the field. Only thing is that it's a Fish and it stands at an unsearchable and unrecyclable 1600/1300. On the other hand, it can handle combat better than LBB if you so wish, and isn't completely helpless on its own.
• Penguin Soldier - It's an old card, but it has a great effect. It has a Flip Effect that lets you bounce 2 monsters on either side of the field. Combos include bouncing the opponent's sole monster and Penguin Soldier itself, and then Setting it again to put the opponent in a bounce lock. However, unlike Flip Flop Frog, you can't flip it down, so no searching via Mother Grizzly for you.
• Aqua Spirit - A Semi-Nomi requiring you to banish 1 WATER monster from your Graveyard. During each of your opponent's Standby Phases, you can change the battle position of one of their face-up monsters, and it can't be changed any further for the rest of the turn. Since you can't actively use this ability immediately, it's intended to be used as defense with Eisbahn to prevent your opponent from attacking you immediately.
• Fenrir - Similar to Aqua Spirit, Fenrir is a Semi-Nomi requiring 2 WATER monsters to be banished. For that effort, what do you get? A monster with a lackluster-looking 1400 ATK but with a very potent effect. If Fenrir scores a kill in battle, your opponent skips their next Draw Phase. Buff Fenrir's ATK enough, and he'll actually make the opponent hesitant to Summon monsters if they want their Draw Phase back.
• Snowman Eater - 0/1900 for a LV3 monster makes it a nice wall and candidate for LV3 or lower support. When Snowman Eater is flipped face-up, you get to destroy a face-up monster. It's a pity that it has no offensive power and won't be able to fully utilize the support available for it.
• The Dragon Dwelling in the Deep (aka DDD) - Each Standby Phase, it accumulates an Ocean Counter. These counters do nothing, but once DDD leaves the field, all your Fish and Sea Serpents (no Aqua) gain 200 ATK per Ocean Counter that was on DDD. Fortunately, this counts both players' Standby Phase, so if the opponent attacks him immediately you get something (meagre) out of this. At least.
• Skreech - With 1500 ATK it's decently strong, searchable, and recyclable. When destroyed in battle, you can mill 2 WATER monsters from your Deck. Why, exactly, would you do that? Maybe to fill the Graveyard for Atlantean Roar, or combine with Salvage to effectively search 2 WATER monsters from your Deck.
• Small Penguin - D'awww... Oh, uhm. If this baby penguin is flipped up and sent to the Graveyard, you can Special Summon a Penguin monster from your Graveyard (besides another copy of it) in either face-up Attack or face-down Defense Position. Use this to recycle your Nightmare Penguins and Penguin Soldier... or simply leave that job to Salvage.
• Metabo-Shark - Decent beatstick stats, and when Normal Summoned, you can shuffle 2 Fish monsters to your Deck. This is better suited for a pure Fish Deck though.
• Hammer Shark - Once per turn, you can reduce its Level by 1 (and let it qualify for any LV3 or lower WATER support) to Special Summon a LV3 or lower WATER monster from your hand. A Special Summon at practically no cost is very much welcome. You can either use this to immediately Xyz Summon, or Special Summon Gillman to get two beatsticks at once.
• Deepsea Macrotrema - If you're using a number of cards that Tribute stuff, Macrotrema can lend a hand in the form of a 500 ATK boost to all your WATER monsters for the turn it gets sent from the field to the Graveyard.
• Uminotaurus - Decent 1700/1000 beatstick that grants all your Fish/Aqua/Sea Serpents the Trample ability. Take this along if you find yourself having a lot of trouble in dealing with indestructable walls.
• Rage of Deep Sea - A LV5 monster with 0/0, but we all know that it's got an effect to make up for that. This late-game tide-turner gains 500 ATK and DEF for each Fish/Aqua/Sea Serpent in your Graveyard. Circumvent the need to Tribute Summon this guy by either using Mother Grizzly or using ALO's level-down effect.
• Big Wave Small Wave - Destroys all WATER monsters you control, and then Special Summons an equal number of WATER monsters from your hand. Maybe useful in surprise-Special Summoning Daedalus, or it can serve to avert dead draws in the LV reduction beatdown variant.
• Field Barrier - Secure your ALO to protect it from destruction by card effects and also to keep your opponent from changing the field.
• Hydro Pressure Cannon - An equip card that requires you to equip to a LV3 or lower WATER monster. This requirement basically screams "use me!" in an ALO Deck. It doesn't grant any ATK boost, but your opponent discards a card from their hand whenever the equipped monster destroys a monster in battle. Looks pretty good when you combine it with a beatstick, but if the opponent pops ALO, Pressure Cannon fizzles out unless that monster's base Level is 3.
• Water Hazard - While you control no monsters, Water Hazard lets you Special Summon a LV4 or lower WATER monster from your hand. Since quite a few WATER monsters depend on the presence of another to become effective, it can prove to be helpful in a pinch. Take care, though, as it has a habit of becoming a dead draw if you use too many.
• Different Dimension Trench - When you first activate this card, you must banish a WATER monster from your hand, field, or Graveyard. But when this card is destroyed, the banished monster is Special Summoned. Banish a large monster and make your opponent somewhat hesitant to throw that Heavy Storm, or combine with your own Heavy Storm for the net effect of a time-delayed Monster Reborn.
• Tornado Wall - It destroys itself if you don't have Umi on the field, but if you do, Tornado Wall prevents all Battle Damage to you from attacking monsters. While it doesn't restrict attacks like other cards, perhaps it can help you last a few more turns.
• Bubble Bringer - Two effects here. First, LV4 or higher monsters cannot attack directly, preventing your demise by a sudden swarm of non-Xyz high Level monsters. Then, during your turn, you can send this card to the Graveyard to Special Summon 2 LV3 or lower WATER monsters with the same name from the Graveyard, though their effects are negated. This clearly screams an immediate setup for a Xyz Summon, or to Summon Poseidra.
• Poseidon Wave - Simply negating an attack isn't very useful. But dealing 800 damage for each Fish/Aqua/Sea Serpent you control? Combo with Atlantean Roar, and suddenly the opponent's lost over 3000 LP.
• Gozen Match - With so many good WATER monsters around, you'll definitely be able to run a Deck filled solely with that Attribute. Side in this card to punish other multi-Attribute archetypes and limit their ability to swarm the field.
• Abysstrom - Yes, yes, I realize it fits better with the Mermails because they search "Abyss" S/Ts, but its effect is general enough for it to be mentioned here. Taking one half of Daedalus' effect into Trap form, Abysstrom lets you send an "Umi" you control to the Graveyard to send all S/Ts on the field to the Graveyard. Handy for bypassing anti-destruction cards that would otherwise prevent you from playing Heavy Storm.