Select exhibition game and repeatedly press L2 and R2 to unlock 2 bonus teams.
The Dingers and Islanders:
Enter exhibition mode, then repeatedly press L2 + R2 until the sound of a dong is heard. The Dingers and Islanders will now be selectable under the 90's teams.
Hit More Homeruns:
While batting, press Square to change from contact to power. Then, line up the upper corner on the side of the batting triangle with the pitching aid. If you swung at the correct time, 90% of the time you will hit a homerun.
Unlock Dingers in batting Practice:
To Unlock the Austin Dingers in batting practice enter batting practice mode and at the team selection mode enter R1 + R2 + L1 + L2.
Switch Team Uniforms:
While your playing a game while u choose a team press L1 or R1 to switch team uniforms.
Thanks to Revolution readers ash, D KID, ron hernandez and Craig Edmondson-Wood!