Get Lots of Points

Begin a two-player game and strike out every batter on each side until you reach 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 tons of points. You can now buy 100 card packs. This should give you every card. If not, repeat and get another 100 card packs. (NOTE: Special cards must be earned in Scenario Mode.)