What's that mean? Well, Boon claims Sub-Zero is roughly equivalent to Batman because they're both the silent-broody-night-ninja type (not sure about Superman and Scorpion though...), so that means the rest of the characters should have some kind of connection. Armed with this information (and a stupidly vast love of comics) we finalized this list of incredibly likely inclusions.
Both are slender, sexy brunettes that kick ten kinds of ass. They're also vaguely villainous bitches that seem to waver on both sides of the law. If one's in, they're both in.
Martian Manhunter and Shang Tsung
Two shape-shifting weirdoes that hardly ever reveal their true form. One blasts fire, the other one's terrified of it. Already makes more sense than Batman/Sub-Zero (which already sounds like awful fan fiction).
Johnny Cage and Booster Gold
It's fun to root for the underdog, even when he's full of himself and could really use a good beating. Odds are they'd make fast friends if they weren't such shameless self-promoters. Energy projectiles ftw!
Kano and Deathstroke (Slade)
If Batman and Sub-Zero can be considered similar, then all we need to connect Slade and Kano is a knowledge of martial arts and lack of binocular vision. They're both well-known and (relatively) down to Earth characters that would make a lot of sense. Our money's on Slade...