Start a two-player game and proceed to strike out every batter on each side until the bottom of the ninth inning.

When you've got two outs at the bottom of the ninth, walk the next four hitters to earn enough points to buy 100 card packs, which should get you almost every card. If not, repeat and get yourself more card packs.

NOTE: This doesn't include special cards earned in Scenario Mode.

This only works if you manage to hit a homerun. Once you do, press in the left joystick to play to the crowd. You can also press R to something similar.

Here is a way to use a cheat card in season mode. Select quick play, then choose teams. Once you're on the chalk board, select cheat (you can only use one at a time). Start the game, and as soon as you can, pause the game and just quit. Now start your regular season, and you'll be able to use that cheat for every game after that.

Say you're ahead in a game and you want to have an ace pitcher ready to pitch within the next few games. All you have to do is throw him one complete inning to raise his stamina.