Cheat mode (enter before the others):
Bases Loaded '96
Start a new game and pause it. While paused, use Controller 2 and press Triangle, Square, X, Circle, Circle
Computer vs. Computer:
Enter Cheat Mode and press L2. To regain control, re-enter Cheat Mode and press L2 again.
For an automatic home run (if you hit the ball), enter Cheat Mode and press L1, then unpause the game. To revert to normal, re-enter the Cheat Mode code and press L1 again.
Enter Cheat Mode and press X to bring up a "Let's Go Inning" menu in the upper left-hand corner. To change innings (up to 18), re-enter Cheat Mode and press X.
Thanks to Revolution readers Aaron Moon!