Mantine's Poké-POWER only works when it is the player's Active Pokémon. Official Wording: Once during your turn (before your attack), if Mantine is your Active Pokémon, you may remove 1 damage counter from 1 of your Pokémon (excluding Mantine). This power can't be used if Mantine is affected by a Special Condition.
Source: PUI Announcement (2004-12-16)

Relevant cards

Note: All applicable cards may not be listed below.
EX7_45