Shadow Ball is a Ghost-typemove introduced in Generation II that has a 10% chance to lower the opponent's special defense by two levels. When using it, a Pokemon creates a dark purple ball in front of its mouth (not all Pokemon). Then the shadowy ball is fired at the opponent.
Several Pokemon can learn Shadow Ball, and all Ghost Type Pokemon can learn it. In the Pokémon Anime, Shadow Ball is best known from being performed by Eevee and its evolved forms.