Three Outs - While playing a game, hold L + R + Z and press Down, Up

Add One Run to Home Team - While playing a game, hold L + R + Z and press C-Left(2).

Add One Run to Away Team - While playing a game, hold L + R + Z and press C-Right(2).

Jump the Green Monster - If you feel the ball is going over the Green Monster run toward the fence and press A, A, A, B, B, UP (on D-pad), B, B, B, A. You will then jump the Green Monster. After about 5 seconds you will apear on top of the Green Monster carrying the ball and waving your hands.

Really Easy Homeruns - When you are batting hold in these buttons, L + R + Z, and then press left, up, left, up on the control pad. If you do this code correct you will hear a thump noise, if you don't hear it then heep on holding in L + R + Z and keep on pressing left and up over and over again. You must do this code everytime before you swing if you want it to work. Example: You enter in the code and the ball is way out side and you don't swing, then you must enter the code again for it to work. This code is really cool and the ball goes almost 1000 feet! You can even hit homeruns while bunting with it on!

Two Strikes On The Batter - When you are pitching hold in these buttons, L + R + Z, and then press right, up, right, up on the control pad. If you did this correctly you will hear a thump sound, if you didn't hear the noise then repeat the code over again. It is really easy to stik epeople out with this code.
Credit Goes To: nOnAMe via N64cc