Enter the following passwords...

ATEMYBUIK - Ultimate cheat: New stadium and aliens
BEST - Choose the AL or NL All-Stars
BIGHELIUM - Big Head and Feet
BRKNBATS - More Broken Bats
GOTHELIUM - Big Head, Feet, and Bat
PRPPAPLYR - 2D Players

Easy Pick-off:

This only works with a runner on second. Select your pitch, then wait for the baserunner to edge past the umpire on the screen, then pick him off. Make sure he's past the umpire.

Little Homerun Derby Guy:

Make sure you have a roster slot open on a team. It should say "empty" instead of a player's
name. Go to HOME RUN DERBY and pick that guy. You won't even see him walking in the grass because he's really small. It takes a while for him to reach the mound, so be patient. Watch the pitcher; he'll actually have to throw to the ground so this guy can hit the ball.

Cheap Fielding Trick:

Here's a nifty little underhanded way to cheat in
All-Star: Wait until you're at bat, hit the ball anywhere, and then quickly pause the game and switch your controller to the other team. That way you can make the outfielder miss the ball, the SS miss an easy grounder, and so on.