Banette is receiving errata for its first attack, Ghost Head. Ghost Head can't cause Banette to Knock Out itself ... the attack has to leave Banette with at least 10 HP. "Put as many damage counters as you like on Banette. (You can't Knock Out Banette.) Put that many damage counters on the Defending Pokémon."
Source: Organized Play News (2008-01-29)

Relevant cards

Note: All applicable cards may not be listed below.
DP3_23