Mike Piazza's StrikeZone

Extra teams: Hit C-Right, A, Down, Left at the title screen.
Watch the credits: Hit R, A, Z, R, C-Right, A, B at the title screen.
Secret message: Hit C-Up, R, B, B at the title screen.

Cheat menu
Go to the pre-game menu,then hit L, R, L, R.
Note: You need to activate this code before
enter any other pre-game menu cheats!

Go to pre-game menu, activate the "Cheat mode"
and press the following button combinations:

Score home runs always: Hit L, A, Down, Right.
Best players: Hit B, A, R, B, A, L, L.
Better pitches: Hit B, L, A, B, R, Z.
Better plays by fielders: Hit B, A, R, Down, L, B.
Better throws by fielders: Hit B, A, L, Down, Z.
Change sky: Hit C-Right, A, Z, C-Up, L, R, Z.
Change to aluminum bats: Hit R, A, Z, B, A, L, L.
Change to blue bats: Hit B, L, B, A, Right.
Change to red bats: Hit R, Down, B, A, Right.
Colorful bats: Hit Z, B, R, A.
Crazy ball: Hit C-Right, A, Z, B, A, L, L.
Crazy pitches: Hit C-Right, A, Z, C-Up, R, B.
Easy steals: Hit C-Left, A, Down, C-Up, Z.
Fast pitches: Hit R, A, Z, L, Down.
Faster fielders: Hit R, A, Z, L, Down, A, Z, L.
Faster game: Hit L, A, Z, R, B, A, L, L.
High gravity: Hit Up, Down, L, Up, R.
Moon gravity: Hit Up, R, A, L.
Slower game: Hit Up, L, L, B, A, L, L.
Unlock Devil's Thumb stadium: Hit Right, A, C-Up, L, A.
Varied pitches: Hit C-Right, A, Z, C-Up, R, L.