Tier 1: Highly Competitive Meta Decks. 10% or more of tops, as ranked by Pojo. This will roughly correspond to Pojo's Tier 1, with some overlap into Pojo's Tier 2.
Tier 2: Semi-Competitive Meta Decks. Less than 10% of tops, as ranked by Pojo. Corresponds for the rest of Pojo's Tier 2, Pojo's Tier 3, and Rogue.
Tier 3: Semi-Competitive non-Meta/Rogue decks. 1-2 tops. Specifically includes decks that top small events or get lower rankings at medium events. Can also include decks that can potentially top but have not yet in a given format.
Tier 4: Casually Competitive non-meta decks. Decks that can compete at the locals level, but cannot top an event.
Archetype Explanation
ABC is a sub-archetype part of the A-to-Z series of LIGHT Machine Union monsters and support. The relevant boss monster in ABC is ABC-Dragon Buster, a Contact Fusion monster. The other main monsters in the deck include A - Assault Core, B - Buster Drake, C - Crush Wyvern, Union Hangar, Gold Gadget, and Silver Gadget. Due to the relatively low monster count there are normally other engines mixed in with the deck. Popular inclusions are True Draco, Brilliant Fusion, Symphonic Warriors, and the Galaxy Soldier Package. Also gaining in popularity is the Destrudo/Dragon Ravine engine.
Tier Ranking
ABCs are currently sitting in Tier 3. This is due to a lot of the natural counters to the deck being main decked in preparation against SPYRALs. The deck is also easily sided against which can make competitive matchups quite difficult. Cards such as System Down and Ghost Reaper & Winter Cherries targeted at ABC are still relatively common occurrences.
Decklists
We'll be taking a look at two different decklists: Calvin Tahan's Top 4 True Draco ABC list from the UDS in Kissimmee Florida and Rodney Hartwell Jr's Brilliant Galaxy ABC list that got 1st Place at the Charlotte North Carolina Regional.
True Draco ABC
This is a build that makes interesting synergies of setting up ABC pieces and sending them to the GY with Dragonic Diagram. This will not only set up the GY with ABC pieces, but will activate the ABC pieces' effects and search a True Draco card. It is extremely reliant on its Field Spells boasting triple Dragonic Diagram, Union Hangar, Terraforming, and Set Rotation. This is useful because Diagram is not a Once Per Turn card allowing it to quickly and effectively find combo pieces. Diagram sends pieces to the GY and tributing a piece in the monster zone with another piece equipped to it will trigger both effects. This particular build also runs very heavy on hand traps as a way to combat the current meta.
Galaxy Brilliant ABC
The Galaxy Soldier package has always been relatively popular in ABC decks. By sending a LIGHT monster to the GY, you can SS out Galaxy Soldier and it will search another one which can also be summoned. This makes for an instant rank 5 which can mean Cyber Dragon Nova into Cyber Dragon Infinity. Transmodify is another card used to change a piece into Galaxy Soldier. This has the dual purpose of triggering the sent ABC piece's GY effects and getting Galaxy Soldier on to the field.
The Brilliant Fusion Engine also sees good use in this deck. Brilliant fusion has a lot to offer to ABC, giving GY setup, an extra monster on the board for Link summoning, and an extra Normal Summon to ensure all of the pieces of ABC are on the field. The deck is already made up exclusively of LIGHT monsters, but there are the additions of Electromagnetic Turtle and Performage Trick Clown as tech options to be sent with Brilliant Fusion or discarded with ABC Dragon Buster. While this build is definitely still strong, it is far weaker than it was before the advent of Link Summoning as Union Hangar and Transmodify can no long lead to a board that consists of both Cyber Dragon Infinity and ABC Dragon Buster, with one or the other having to be preferred unless a Link monster can manage to be summoned first. Fortunately, the combination of the Gadget monsters, Brilliant Fusion, and Trick Clown give the deck additional fodder with which to summon out a Decode Talker.
Tech Choices
Dragon Ravine Engine
The core part of the engine is Destrudo the Lost Dragon's Frisson. This card can be sent to GY by Dragon's Ravine, setting it up to be summoned to the field if you control any level 6 or lower monster. Destrudo is primarily used to summon Ancient Fairy Dragon which can in turn destroy Dragon Ravine and the opponent's Field Spell to search a Union Hangar. Ancient Fairy Dragon also has the added benefit of being able to out the Set Rotation lock, something that is increasingly common with the meta relevance of SPYRAL and something that can prove particularly deadly to ABC.
The Dragon Ravine engine can also optionally run Supreme King Dragon Darkwurm as an additional target for Dragon's Ravine. This card can summon itself from the GY if there are no monsters on your field, giving it a similar purpose to Photon Thrasher.
In addition to these monsters, the Dragon Ravine engine also offers easier use of Set Rotation. This is an increasingly popular card in the meta as SPYRAL become more prevalent and can serve as a very strong counter against them. Set Rotation also increases the consistency with which ABC can get to Union Hangar which is key to getting out ABC Dragon Buster as fast as possible.
Symphonic Warrior Engine
This engine consists of 2-3 copies of Symphonic Warrior Guitaars and 1-2 copies of Symphonic Warrior Miccs.
Both cards are Machine monsters (unfortunately they are WIND), but the extra NS provided by Miccs give the engine value in the deck. The engine does largely function, however, as a more budget version of the Brilliant Fusion engine due to it costing a discard to start instead of sending a card from the deck to the GY.
Predaplant Engine
This engine consists of 3 Predaplant Ophrys Scorpio and 1 Predaplant Darlingtonia Cobra. The main benefit it offers is to search out Brilliant Fusion more quickly while also providing Link fodder. While this engine is undoubtedly very powerful, the additional inconsistency that it offers, having to be run alongside Brilliant Fusion, is usually enough to turn most ABC builds away from it. The advent of new Link monsters that more easily utilize the Predaplants might see this catch on more, however.
Matchups
SPYRAL
This is unfortunately one of the weaker matchups for ABC as there are many natural forms of disruption main decked in SPYRALs. With the reliance on a single Extra Deck Monster like ABC Dragon Buster, Ghost Reaper & Winter Cherries can be deadly. Because of this, some players may have a copy of ABC-Dragon Buster just for this particular matchup which will end up in a blowout.
Although there is no easy win card versus SPYRAL, the best strategy to focus on using hand traps to prevent the SPYRAL player from constructing a board. While SPYRAL is extremely explosive, if ABC is able to get the game into a simplified state, they can often swing the advantage decisively in their favor and win the game.
Paleozoic
Paleozoics are capable of outgrinding ABC's as the form of disruption from Dragon Buster is costly by requiring a card in hand. This makes you burn through resources much faster which is something that Paleo decks won't mind at all. Many of the cards run such as Paleozoic Olenoides and Paleozoic Canadia can also heavily disrupt plays by preventing Link summoning or stopping Union Hangar from successfully getting a search. The main cards to use in the matchup are Spell/Trap destruction cards such as Cosmic Cyclone and Twin Twisters to try and prevent the opponent from amassing too many Traps.
True Draco
ABCs have a pretty fair matchup against True Draco. Due to Dragon Buster's effect banishing as opposed to destroying, True Draco can easily lose the trades in advantage they normally gain from the GY effects of their Spells and Traps. ABC Dragon Buster can also run over Master Peace if there isn't a Diagram present and its ability to dodge being destroyed on the opponent's turn makes it a tricky card to handle.
The main cards to be used against the matchup include Spell/Trap removal and hand traps such as Ash Blossom & Joyous Spring, Ghost Ogre & Snow Rabbit, and Droll & Lock Bird.
Trickstar
ABC players may find themselves infuriated going against this deck if they get locked out of their hand with Droll & Lock Bird or Trickstar Reincarnation. If the ABC player is able to rely on the True Draco variant or make Dragon Buster without the help of Terraforming and Union Hangar then they should find themselves faring in a good position. Something interesting to counter Trickstar with are the same cards that many ABC decks already run to counter System Down: Union Scramble and Pot of Acquisitiveness. Both of these cards can help the ABC player recover advantage lost by Trickstar Reincarnation and can decisively swing a game back in the ABC player's favor. Set Rotation is also particularly powerful against Trickstar as many Trickstar players don't have an easy method to out the lock.
