"Goblin" (Japanese: ゴブリン Goburin) is an archetype based on "Goblin Attack Force" and "Goblin of Greed", and their variations. The theme didn't have any support until The New Challengers, in which "Scrounging Goblin" was released.
Most members share the effect "If this card attacks, it is changed to Defense Position at the end of the Battle Phase, and its battle position cannot be changed until the End Phase of your next turn." (though not necessarily with the same wording) and also share 0 DEF.
Most "Goblins" have an enormous advantage in ATK. "Goblin Attack Force" clocks in at 2300 ATK, "Goblin Elite Attack Squad" brings 2200 ATK to the table and "Goblin Black Ops" is relatively big for a direct attacker, having 1300 ATK. Because of this advantage, "Goblins" may be the archetype with the strongest Level 4 monsters. However, though "Goblins" have several advantages in form of their original ATK, they almost all have a drawback that makes a Deck containing them somewhat hard to use. The drawback is that after most "Goblin" monsters battle, they must change into face-up Defense Position. To prevent this drawback from destroying your overall strategy, you can add copies of "Final Attack Orders" or simply use them for Link or Xyz Summons to circumvent the issue of having 0 DEF monster as your final line of defense.
The "Goblin" archetype has one main searcher in form of "Scrounging Goblin" who not only has the chance of fetching cards from the opponent's hand but also searches for almost any card with "Goblin" in it. This widens the search pool to a number of cards that originally didn't have to do anything with the green heavy hitters. The weird search effect can give you cards like "Upstart Goblin" or "Good Goblin Housekeeping", which help in the consistency department or supportive cards like "Robbin' Goblin", which will diminish the resources of your opponent.
Both "Scrounging Goblin" as well as "Goblin Recon Squad" need to deal damage to the opponent to trigger their effects, making "Moon Mirror Shield" helpful. The additional damage also helps in edging the opponent nearer to 0 LP, which is undeniably the overall strategy of a Beatdown-heavy "Goblin" deck.
Unfortunately, "Goblins" are very slow, and have a hard time doing more than one Normal Summon per turn. To circumvent this issue, cards like "Marauding Captain" and "Goblindbergh" can be used to up the number of monsters per turn and therefore allowing for easier access to the Xyz and Link monsters.
You can also use "Skill Drain" to prevent the effects of the big boys which would put them into defense while negating your opponent's card effects at the same time. You can also use "Zero Gravity" when most of your strong "Goblins" are in defense to switch them to attack, or for an added bonus use "Gamushara", potentially killing the opponents monster or dealing a nice sum of damage. Further Floodgates that can be added are both "Dimensional Fissure" and "Macro Cosmos", since the "Goblins" hardly ever work with the Graveyard and therefore don't really mind their cards being banished.
- "Goblins" rely on monsters and the battle damage done by them, and will therefore crumble if their monster line-up is constantly destroyed via "Raigeki", "Dark Hole" or "Interrupted Kaiju Slumber".
- By the same token, any form of summon negation can mean a killing blow for the green horde, making "Solemn Judgment", "Solemn Warning" or any similar effect very effective against them.
- Defensive and control-oriented decks can have a field day with this deck due to its limited access to removal and control options; those decks can slowly block and halt any dangerous advances from the "Goblin" player while building a very cozy board position for themselves.