Backyard Baseball Cheat Codes for Gamecube

Better bats:
To get a special bat (in any mode except tee-ball) you must get a double play. You can walk a man. When the other player comes up, he might hit a single. Note: Get a fast pitcher to run to first and tag the player out. Note: Sometimes you may strike out the person or not get him if you have two outs.

Home Run Derby:
Note: You have to be fast. Choose two people and select a third person immediately before the screen changes. This will help you get more hits and home runs.

Aquadome:
Hit a homerun into the pool at Steele Stadium, into the swamp at Gator Flats, and into the lake at Frasier Field. The Aquadome stadium should now be unlocked.

Easy second base:
If the other team throws the ball to home play and you are on first base, you can run to second and they will not see you.