From BR Bullpen
An ambidextrous pitcher has the very rare ability by a pitcher to throw both left-handed and right-handed. This would potentially allow a pitcher to always have the platoon advantage against a right-handed or left-handed batter or even a switch hitter. Against a switch hitter the batter would need to commit to a side while the pitcher could choose which hand to use.
Ambidextrous pitcher Pat Venditte has been pitching in the minor leagues since 2008 and caused the Professional Baseball Umpire Corporation to create a new rule (Rule 8.01) regarding ambidextrous pitchers stating that a "pitcher must visually indicate to the umpire, batter and runner(s) which way he will begin pitching to the batter."