Pokémon Black Version and Pokémon White Version - PP
Whenever a Pokémon starts to use a move, that move is reduced by 1 PP. If the PP can’t be reduced this way, the Pokémon doesn’t use that move instead. (A move that can’t be used because it has zero PP is not considered to fail {and is not "prevented from being used"}.) {(If the move is taken with Snatch or Magic Coat, the new user doesn’t lose PP for that use, even if it also has that move.)} A move with zero PP can’t be chosen for use until its PP is restored. The PP check is done after all other checks before a move is used.