Well it makes it less fun when you don't want super-strong characters. Characters like Galactus and Ego are too large and odd to include, but I want to say Loki, Mephisto, and Thanos for the bad side and Thor, Silver Surfer, and Hulk for the good. If the characters have to be fairly normal, then I say Spider-Man, Wolverine, and Captain America. That would be interesting to see which hand-to-hand fighter would come out on top.