"Scrap" (スクラップ Sukurappu) is an archetype of EARTH monsters that debuted in Duelist Revolution. They are used by Toru in Yu-Gi-Oh! 5D's World Championship 2011: Over the Nexus, Heartland Tower Security Robot in Yu-Gi-Oh! ZEXAL and Battle Braver in Yu-Gi-Oh! VRAINS.
The Scrap-Iron series is not a part of this archetype, since its Japanese name, 「くず
As their name suggests, "Scrap" monsters are all made of old, rusty fragments of steel, but in spite of their appearance and name, to date, only 4 of these monsters are Machine: "Scrap Hunter", "Scrap Mind Reader", "Scrap Breaker" and "Scrap Recycler".
"Scrap" is discarded metal for reprocessing.
"Scrap" monsters focus on destroying one another with their own effects (maybe reflecting the fact they are made of scrap, being fragile and easily collapsible) and setting up Synchro Summons. "Scrap Worm", "Goblin", "Kong", "Soldier", "Orthros" and "Beast" can add 1 "Scrap" monster from your Graveyard to your hand when they are destroyed by the effect of a "Scrap" card. The difference between them lies when these destroying effects activate: "Scrap Orthros" can quickly Special Summon itself if you already control a face-up "Scrap" monster, but it costs a "Scrap" monster when Summoned this way; "Scrap Goblin" cannot be destroyed by battle, but if it is attacked while in face-up Defense Position, it destroys itself at the end of the Battle Phase, etc. You can take profit of these self-destroying effects by chaining "Scrapstorm" and/or "Scrap Sheen" to their activations, as well as by using "Scrap Factory" to Special Summon almost any "Scrap" monster from the Deck, when another one is destroyed by a card effect and sent to the Graveyard, either by their own effects, or by a general one, such as "Raigeki", "Sylvan Marshalleaf", "Artifact Moralltach" etc.
They also have Deck-thinning capabilities, either by searching for monsters ("Scrapyard") or by sending them to the Graveyard ("Scrap Shark" and "Scrapstorm") in order to set up the game for monsters like "Chimera" or "Golem".
The ace cards of the Deck are its Synchro Monsters, namely "Scrap Dragon", "Scrap Twin Dragon" and "Atomic Scrap Dragon". Their effects destroy 1 card you control and target up to 3 cards on your opponent's possession. The first monster simply destroys 1 of your opponent's cards, the second one returns exactly 2 cards your opponent controls to the hand and the third one shuffles up to 3 cards from their Graveyard into the Deck. They are very flexible, and you can use them depending on what your opponent has: "Scrap Twin Dragon" can deal with cards "Scrap Dragon" can't, such as "Beelze of the Diabolic Dragons", "El Shaddoll Winda", "The Seal of Orichalcos" and "Ultimate Axon Kicker"; "Atomic Scrap Dragon" can thwart some possible strategies of your opponent by shuffling monsters like "Satellarknight Deneb", "Mezuki" and "Grapha, Dragon Lord of Dark World" into the Deck; you can use their effects to destroy a "Scrap" monster you control in order to trigger its effect. Finally, each of these Synchro monsters compulsorily Special Summons a non-Synchro "Scrap" monster from your Graveyard when they are destroyed by your opponent's card (either by battle or by an effect).
Since the Deck relies basically on the Trigger Effects activated when the "Scrap" monsters are destroyed and sent to the Graveyard, cards like "Soul Drain" and "Macro Cosmos" can be used. Also, "Rivalry of Warlords" can be a good counter, due to its variety of Types. With "Scrap Golem" and "Scrap Factory", they tend to have a good swarming capability, so cards like "Kaiser Colosseum", "Summon Limit" and "Summon Breaker" can also be used; you can also opt to cards that totally stops Special Summons, such as "Jowgen the Spiritualist", "Vanity's Emptiness". "Tualatin" can completely shut down the Deck since every "Scrap" monster is EARTH-Attribute.
Once the deck rely on setting up the game for the Synchro Summoning of their ace cards, "Discord", "Grisaille Prison", "Orient Dragon" and "Shiny Black "C"" can either significantly paralyze their field presence or remove them completely and without at least one of the "Dragons", many of the other "Scrap" cards lack decent field control.
Their heavy reliance on "Scrap Factory" also makes cards which negate the effect or simply remove it very detrimental to their swarming ability;It also means that their ability to consistently end with a strong board is limited.