- The Poké-BODY "Knockout Gas" found on Koffing should read, "If Koffing is your Active Pokémon and is Knocked Out by damage from an opponent's attack, the Attacking Pokémon is now Confused and Poisoned." So only attacks that do damage (not "place counters") would cause Knockout Gas to be invoked.
Source:
PUI Rules Team (2005-06-23)