This trick will get you free Thunder Plates. It's a fairly simple trick, but there is a certain way it needs to be done.
1) Go to 2-player mode and go to "Thunder Plates." You need both players to load the same platebook (it can be done), then to "Trade Plates." 2) Trade the various plates, making sure that Player 1 has the better plates. Then cancel the trading and save the platebook for Player 1 ONLY and not Player 2. 3) The platebook should now have all the plates traded from Player 2 to Player 1. This filters out your bad plates to get more of your good ones, if you trade correctly.