First reason for his inclusion in the game: He looks cool as all hell.

Second reason: Superman once said that "he is the most powerful being on the face of the Earth." Whoa. Martian Manhunter can go ham on his fellow heroes and despised villains with the powers of super strength, flight, vortex breath, and “Martian Vision.” Don’t be in his direction when he hands out a nice energy beam from his eyes.