- Strength Charm should read: "Whenever an attack from the Pokémon that Strength Charm is attached to does damage to the Active Pokémon (before applying Weakness and Resistance), the attack does 10 more damage. At the end of the turn in which the player attacks with the Pokémon that this card is attached to, discard Strength Charm." This errata replaces text of "after applying Weakness and Resistance" with "before applying Weakness and Resistance" [in the Team Aqua vs Team Magma print]. It is also clarified that it is removed after ANY attack that the Pokémon makes, not just attacks that do damage.
Source:
PUI Announcement (2004-10-01)