They are divided in 3 different sub-Archetypes, the Abnormage, monsters that reside in the Main Deck; the Abnormagus, monsters that reside in the Extra Deck; and the Abnormagic, the Spell/Trap cards of the archetype.
The "Abnormag" monsters do not have an actual illustration (since CardMakerDoge is simply terrible at drawing). Although, the concept for their art would have deformities in their bodies, such as extra limbs, disproportionate limbs and etc.
The Main Deck "Abnormag" monsters all have different Levels and a Pendulum Scale equal to their respective Levels. All of them have the Pendulum Effect "You can only Pendulum Summon "Abnormag" monsters", followed by an Pendulum Effect that activates whenever a monster is shuffled into the Deck, and another one which allows the card to be shuffled into the Deck during the turn it is placed in the Pendulum Zone in order to activate an effect.
Their regular monster effects are one that activates when they are Pendulum Summoned and a second one which can be triggered when a monster is shuffled into the Deck, allowing them to shuffle themselves alongside with that card to activate an effect.
The Extra Deck monsters are all Level 12 Spellcaster Synchro Pendulum Monsters which require an "Abnormag" Tuner and 1 or more non-Tuner monsters to be summoned. All of them have Pendulum Effects, and effect that activates when they are summoned, and an effect that can be activated for the cost of shuffling one monster your opponent controls into their Deck.
Their playing style focuses heavily on Pendulum Summoning and shuffling monsters into the Deck. Due to their Pendulum Effects, pure Abnormag Decks would probably do better than hybrid Decks using the archetype.
Since their Pendulum effect that doesn't allow non-Abnormag monsters to be Pendulum Summoned CAN be negated, then cards that negate Pendulum Effects might be useful,