The Hood's Gang vs Wetworks (All members)
All of Hood's Gang vs All of Wetworks. I know Wetworks are outnumbered, but they have fought armies before.
http://www.comicvine.com/the-hoods-gang/65-50921/characters/
vs
http://www.comicvine.com/wetworks/65-40403/characters/
No Dormammu, of course.