It is beautiful when characters from different shows cross over into other shows but doing it in your head is much more fun. My favorite battle scenario is the Justice League VS. Avengers. For those of you who do not now the avengers (they are fairly new) they are basically the heroes you have already seen that were not given actual cities to defend. Anyway that scenario is my favorite to think about. The fun thing about this is you get to be as accurate as you want or even use cheats. My cheat is giving Iron man kryptonite so he can kill Superman. Whats your favorite imaginary showdown?