Original URL: http://www.psxextreme.com/ps2-cheat-print/271.html
High Heat Major League Baseball 2004

Cheat mode:

Pause game play and press Square(2), Circle(2), L1, R1. A sound will confirm this portion of the code. Then, press L1 + L2 + R1 + R2. The "Ball Cannon" (set pitch physics) and "Game State" (edit game parameters) options will now be unlocked. 

Note: After using the "Game State" and "Ball Cannon" cheats, if you do not save soon afterwards, your game may freeze. 

Fights:

Hold Square after your batter is beaned and he will charge the pitcher and start a fight. Your player will be ejected.

Thanks to RamirezXsJ