If you are a left handed hitter at bat, press R
+ Left gently, and R + Down gently before the
pitch. If you are a right handed hitter at bat,
press R + Right (gently), and R + Down (gently)
before the pitch.
We have All-Star Baseball 2003 cheats for PlayStation 2, Xbox, Game Boy Advance, and GameCube on CheatCodes.com. Give them a try, since cheats for other game systems sometimes work on Game Boy Advance games, too!