During gameplay, type in these codes:
Keyboard
Hold down the 1+2+3+4 keys on the keyboard (not the NumPad) and enter these cheats. Use the arrow keys for the Left, Right, Down and Up.
LEFT, SHIFT, RIGHT, ALT - Sponsor comment
ALT, RIGHT, SHIFT, LEFT - Nickname game
DOWN, CTRL, RIGHT, ALT - Stadium info
SHIFT, LEFT, LEFT, SHIFT - Crowd cheer
CTRL, DOWN, DOWN, CTRL - Crowd ooh
ALT, RIGHT, RIGHT, ALT - Crowd boo

Sidewinder Gamepad
Hold down both trigger buttons plus Y and Z, and enter these cheats.
X, A, X, C, B, A, LEFT, RIGHT - Home run
UP, DOWN, X, A, X, C, B, A - Strike out
UP, X, RIGHT, C - Histrical commentary
X, UP, UP, X - Crowd cheer

Gravis Gamepad Pro
Hold L1+L2+R1+R2, and enter these cheats.
BUTTON 4, B1, B4, B3, B2, B1 - Home run
UP, DOWN, B4, B1, B4, B3, B2, B1 - Strike out
UP, B4, RIGHT, B3 - Historical commentary
B4, UP, UP, B4 - Crowd cheer

Secret Stadiums
1. Turn off User Records mode.
2. Go to the Stadium Select Screen.
3. Scroll all the way to the right
(Houston will be on the top left).
4. Click on Houston, and contiunue clicking diagonally downand to the right (Houston-top left, middle stadium, bottom right stadium)
5. Now click in a line diagonally up and to the right, bottom left, middle stadium, top right stadium)
6. If done right you will hear TRIPLE PLAY. Scroll to the right and you will have three new stadiums.