Thanks to the eyes of Zmoke, if you look closely enough at the 'Battle Edition' fightstick, you'll clearly see Doomsday hiding behind. The only reason we're not saying revealed for sure is lack of official word as of yet, but it's pretty obvious nonetheless. Doomsday is one of the most ferocious characters in the DC Universe and is quite the foe of Superman. In fact, in a comic called "The Death of Superman" released in 1992, Doomsday killed Superman. "He is a nearly mindless, berserk killing machine, with no feelings or sentiments beyond unfocused hatred, murderous rage, and the sheer malicious joy of destruction."
Thanks again to @Zmoke for the tip and the good eye!