3. Swamp Thing
How this one isnt already included in the game is a total mystery to me. One of the darkest heroes in DCs lineup is the protector of the Green. Whether he is a part human or full vegetation Swamp Thing is terrify threat to those that try to terrorize those that triumph. Honestly, within the context of hero vs hero Swampy is perfectly set up to be Injustices version of Scorpion. As with most (or, well, virtually all) of the characters that Netherrealm Studios are using the character could be utilized differently based on which version that they chose to use. Obvious leading candidate is the full plant, elemental energy version from the pinnacle of Swamp Things run the Alan Moore version. They could also go with the current iteration of the character that Scott Snyder just finished up. With Blackest Night DLC skins how awesome would a DLC expansion be that featured the Rotworld arc?