How exactly does this work? Does it mean that you can choose any of your opponent's Pokèmon, or is it restricted to the Active Pokèmon?
Pokè-POWER Plymimic
Once during your turn, instead of Alakazam’s normal attack, you may choose 1 of your opponent’s Pokèmon’s attacks. Alakazam copies that attack including its Energy costs and anything else required in order to use that attack, such as discarding Energy cards. (No matter what type that Pokèmon is, Alakazam’t type is still Psychic.) This power can’t be used if Alakazam is affected by a Special Condition.
(Image of Alakazam: http://www.pokebeach.com/sets/expedition.html )
Pokè-POWER Plymimic
Once during your turn, instead of Alakazam’s normal attack, you may choose 1 of your opponent’s Pokèmon’s attacks. Alakazam copies that attack including its Energy costs and anything else required in order to use that attack, such as discarding Energy cards. (No matter what type that Pokèmon is, Alakazam’t type is still Psychic.) This power can’t be used if Alakazam is affected by a Special Condition.
(Image of Alakazam: http://www.pokebeach.com/sets/expedition.html )