Generation Iii
Trace
Copies special ability.
Detailed Effect
When this Pokémon enters battle, it copies a random opponent's ability. This ability cannot copy Flower Gift, Forecast, Illusion, Imposter, Multitype, Trace, Wonder Guard, or Zen Mode.
Pokémon With Trace
7 canonical Pokémon forms can have this Ability.

Porygon
Porygon2
Ralts
Kirlia
Gardevoir
Mega Alakazam
Mega Meowstic