Activate the following cheats by pausing the game and pressing the corresponding sequences of buttons:

CHEAT FUNCTION - CHEAT CODE
Faster players - LEFT(3), UP, RIGHT(3), DOWN.
Faster pitch speed - UP(2), LEFT, RIGHT, LEFT, RIGHT, UP(2).
Slower players - RIGHT(3), UP, LEFT(3), DOWN.
Big heads - LEFT, RIGHT, UP(2), LEFT, RIGHT, UP(2).
Small heads - LEFT, RIGHT, DOWN(2), LEFT, RIGHT, DOWN(2).
Big ball - UP, RIGHT, DOWN, LEFT, RIGHT, DOWN, LEFT, UP.
Game developer starters - LEFT, DOWN, UP, RIGHT, LEFT, DOWN, UP, RIGHT.
Disable sound effects - UP(2), DOWN(2), LEFT, RIGHT, LEFT, RIGHT.

Guessing a four seam fastball every time increases your chances of hitting the ball and hitting it further.

While playing the game in Season mode, press START and go to the options, then go to "User Game Tuning" and increase your contact and power until it is a full bar. You can now hit a homerun with almost every at bat.

Start a game, score a run, and press Start. Then, go to "Fast Forward" and select "End Of Game" and you will win.

If you hit the ball and it goes to the entrance of a dug out, the opposing team will try to pick it up but won't be able to, resulting in an inside the park homerun for you.