Sounds like a pickup line at a comix con – “Hey, baby, how would your Swamp-Thing like to meet my Man-Thing?”
How about some crossovers between Marvel and good ol’ Harvey Comics?
Hot Stuff meets Mephisto
Wendy the Good Little Witch meets the Enchantress
Baby Huey meets Howard the Duck
Stumbo meets the Hulk
Little Lotta meets the Blob
Little Dot meets Bullseye
Richie Rich meets Wolverine. And Sabertooth. Right after they’ve both been put through a six-week Marxist revolutionary indoctrination course and been injected with a massive cocaine-methedrine-LSD-PCP speedball.
For once and for all…Batman/Captain America. For this to work best, maybe it should be some kind of alternate universe story where we don’t have to worry about everything going “back to normal” by the end.
You might want to check out Batman/Captain America by John Byrne, which starts in World War 2 and is completely contained within its own little universe (much like Byrne’s Generations series; in fact, they might be the same universe, although I’m not sure). It’s a pretty fun story, and a rare case of DC work by Byrne that doesn’t feature Darkseid and a bunch of Parademons for no reason.