DC Earth vs Marvel Earth
-pre-52 for DC
-all characters that are permanently based and live on Earth in 2010 (no characters that only exist in the past or future)
-only "standard" versions of each character (no amped, possessed, super-charged, or otherwise special versions)
-no prep, although everyone has access to whatever tech and resources they normally have
-bloodlust on for both sides
Both Earths suddenly appear orbiting each other in a unified reality. Each side fully believes the other is evil and must be destroyed at all cost. Each side's objective is to kill everyone on the other planet, even if that includes destroying everything on the planet including cities. While everything on each planet can be affected and destroyed, each planet also has an energy field that keeps it intact. This allows characters to use as much force as needed without risking destroying the planet and therefore affecting their own homeworld. It's not known what's causing this force field, but presumably it's whatever power teleported the two Earths together in the first place.
Win when everyone on the other planet is dead or permanently incapacitated.
Which side wins? How? Who are the key characters for the winning side? Who's left alive when it's all over?