EA All Stars:
Goto the Team Selection Screen in the single game mode and enter the following:
Left, Right, Left, Right, Left, Right, Left, Right, Left, Right, Left, Right,
You will hear 'Triple Play Baseball' if you entered it successfully!

Throwin' Heat(season mode):
Pitch 6 strikeouts in a row.

Big Ball(season mode):
Pitch 9 strikeouts in a row.

Skinny Head(season mode):
Strike out 6 times in a row.

Big Stick(season mode):
Hit 2 home runs in a row.

Super Arm(season mode):
Get caught stealing 2 times in a game