Antimaterion (アンティマテリオン Antimaterion) is an Archetype used by Yuko Tsukumo in Taylor Gorrell's and XBrain130's fanfiction universes. The members of this Archetype are of varying Attributes, Types, and Levels, but all have skin colors matching their Attribute, as well as robes of varying shades of the same color (Antimaterion Xyz Monsters wear robes that have multiple colors but are still predominantly their matching color). All members' names start with "X", "Y", or "Z", and have whatever letter their name starts with marked in white somewhere on their bodies.
Antimaterion Decks focus on Xyz Summoning very quickly, but they do so through an unorthodox method: If an Antimaterion monster is on the field with another monster of the same Level, then an Xyz Monster of a matching Rank can be Xyz Summoned with no Xyz Materials, leaving the two monsters free to be used in a second Xyz Summon. This effect can only be used once for each monster while on the field, and monsters Summoned by this effect cannot attack. (The no-attack clause does not exist in Taylor Gorrell's fanfictions, and in those same fanfictions, this effect is usable by each monster once per turn rather than only once while on the field). However, these effects can stack, meaning a player can feasibly Xyz Summon up to three times with the same two monsters in one turn. Antimaterion Xyz Monsters play off this, with none of them having effects that require Xyz Materials to be detached, and many of them having effects that either require them to have no Xyz Materials to use, gain bonuses for other Xyzs with no Xyz Materials, or punish Xyz Monsters that do have Xyz Materials. Several Antimaterion Xyz Monsters are also non-Effect Monsters, leaving the player free to use Normal Xyz Summons without breaking the strategy. Their support largely focuses on keeping the Xyz Summons coming, usually by Summoning other Antimaterions of matching Levels or simply Xyz Summoning outright from places other than the Extra Deck.