As soon as the user comes into battle, it transforms into its opponent. Imposter copies the target’s appearance, cry, moves (which all have 5 PP),Ability, stats (except HP), stat changes (but not stat multipliers such as with Choice Specs), weight, and Mega Evolution or form (regardless of held item). Imposter does not copy its opponent’s IVs (for the purpose of Hidden Power), friendship or gender.
Imposter will not activate if the opponent is transformed, disguised with Illusion, or behind a substitute. Imposter only activates when the Pokemon that has it is sent out; if it fails to transform into an opponent, it will not activate unless the Pokemon with Imposter is withdrawn and sent out again.
In Double and Triple Battles, Imposter will copy the opponent in the position directly opposite it. If there is no opponent directly opposite to it, it will not transform.
Outside of battle
Imposter has no effect outside of battle.
Pokemon with Imposter