Cheats:
At the Match-Up screen, press X, Y, and B to change the icons in the first, second, and third boxes. The numbers below indicate the number of times each button is pressed. Press the D-pad in the specific direction to activate the code.

More time to enter  3-0-3 Up

Rubber ball         2-4-2 Up 

Soft ball           2-4-2 Down 

Ice bat             0-0-3 Up
Sword bat           0-0-2 Up

Bone bat            0-0-1 Up
Log bat             0-0-4 Up
Wiffle bat          0-0-4 Right
Mace bat            0-0-4 Right
Maximum speed       0-0-3 Left 

Maximum power       0-3-0 Left 

Maximum batting     3-0-0 Left 

Big heads           2-0-0 Right 

Small heads         2-0-0 Left 

Unlimited turbo     4-4-4 Down 

Tournament mode     1-1-1 Down 

No fatigue          3-4-3 Up 

No contact mode     4-3-3 Left
Sub-Zero Team       1-2-2 Down

Rodeo Clown Team    1-2-3 Down
Little League Team  1-0-1 Down
Gladiator Team      1-1-3 Down
Bobblehead Team     1-1-3 Down
Midway Park         3-2-1 Down

Thanks to Revolution readers Alex A, Joe Flax, John Turner, and Martin Brodeur!