CheatOgre.com: All-Star Baseball 2003

Infinite points
You can gain points for certain feats performed during a game. You can use these points to buy cards which unlock cheats, stadiums, jerseys, producers, and players. An easy way to get a lot of points is to throw a perfect game. This is worth 100 points. Switch controls every time the CPU is up at bat and intentionally strike out. This will get you points for 27 strikeouts, and for a perfect game. Repeat this as many times as needed to get an unlimited amount of points.

Extra points
To get more points in franchise mode to sign your free agents, during the off season either create a player and pick him up as a free agent or sign free agents and release them at the end of the season.

Control homerun replay
After hitting a homerun, a replay of it will be displayed. When you see your batter heading home from third base, press various buttons to see different camera angles.