Haven't done this yet, and don't know whether or not I actually will, but it occurs to me that one could 'play' one villain against another villain with no heroes at all, just to see what would happen. Whenever a villain card mentions a hero or hero target, it would refer to all of the targets of the other villain.
I wonder if Baron Blade would have a tremendous advantage in this sort of scenario, winning by getting his trash full.
it would be difficult to pull this off without some kind of smart targeting.
For example, many villains target the villain target with the highest hp, which if facing off against BB, it would be BB. However BB is immune to damage until the platform goes down, making for about a jillion wasted attacks, and making BB pretty good in this situation. Despite this, my money is on Omnitron, Cosmic Powered Exterminator/ Sentient Dropship. Electropulse explosive is too powerful for most villains to stop.
Well, also given that many villains "attack" equipment, that equipment is a hero only card type, and that the only villain only card type equivilant is a device, maybe anything that destroys equipment should also destroy opponent's devices. That should also knock Baron Blade down a peg.
I think we need to do a "celebrity death match" with this to see who is king of the villains. If I get time, Ha!, I'll do it and write it up.