MLB 08: The Show
All classic stadiums
At the main menu, press Down, Right, Circle, Square, Left, Triangle, Up, L1 to unlock all classic stadiums. If you entered the code correctly, the controller will vibrate. It will not show up on your profile, but it does work in Exhibition mode.
All Golden and Silver era players
At the main menu, press L1, L2, Square(2), Triangle, Circle, Down to unlock all Golden and Silver era players. If you entered the code correctly, the controller will vibrate. It will not show up on your profile, but it does work in Exhibition mode.
Easy training points
When you are a pitcher in Road To The Show mode, a good way to get extra training points is to catch every possible pop up you can reach on the infield. One out is worth 5 points, two outs are worth 10 points, three outs are worth 15 points, and it goes up. Make sure you can easily reach the pop up. If you get to the ball at the same time it is about to reach the infielder who is calling for the pop up, it may fall in.
The image featured at the top of this post is ©The Legend of Heroes: Trails of Cold Steel III key art.