Illusion will change the appearance of the Pokemon to that of the last Pokemon in the player’s party. Illusion will not disguise the Pokemon if the last Pokemon in the player’s party is fainted or is of the same species. Illusion will replicate the type of Poke Ball, nickname (or species name if none), Shininess (if any), gender, and form of the Pokemon it is masquerading as; however, it does not replicate the level of the masqueraded Pokemon. The effect is only aesthetic: it does not affect the Pokemon’s stats, type, moves, etc.
The illusion wears off—causing the Pokemon with this Ability to appear as its true self—when the user is damaged directly by a damaging move or when Illusion is negated or replaced. Indirect damage or loss of HP (such as through Substitute, Life Orb, weather conditions, status conditions,entry hazards, recoil, and so on) will not break Illusion. If the Pokemon with Illusion is hit by a multi-strike move, the illusion will be broken after the first hit.
A Pokemon with Illusion can masquerade as another Pokemon with Illusion, provided that they are different species.
Illusion cannot be Traced, copied with Role Play, or swapped with Skill Swap. If a Pokemon other than Zorua or Zoroark obtains this ability with Imposter or Transform, the Pokemon will not copy this ability.
Illusion can now mimic another Pokemon with Illusion of the same species.
Illusion now disguises the Pokemon as the last conscious Pokemon in the party.
Outside of battle
Illusion has no effect outside of battle.
Pokemon Mystery Dungeon
In Pokemon Mystery Dungeon: Gates to Infinity, the Ability functions similar to the main series games for foe Pokemon. A Pokemon with this Ability can transform into another Pokemon that can be found on the same floor of a mystery dungeon. For partner Pokemon, this Ability becomes nonexistent.
Pokemon with Illusion