system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel/DC] What happens if the villains switch universes?

Iron Man swaps villains with Batman
Cap swaps villains with Flash
Spider-Man swaps villains with Aquaman
Thor swaps villains with Superman

Etc etc 

Edit - sorry - didn't mean to restrict the 'swaps' - generic universe swap is fine! Thanks for all of the responses!
gpt
Well... Right off the bat, cap gets annihilated by one of the speed force villains, and superman gets murdered by magic. Thor is probably killed by Zod, spiderman drowns, aquaman gets ignored.

Iron man and batman swap pretty well. Iron man's villains are woefully unprepared for the bats planning and sleuthing, and the bats villains can't remotely compete with iron man's armoury. The Joker is completely fucked. Stark would lose patience right quick and end the threat with extreme prejudice.

The flash fares extremely well. None of caps villains would pose any threat to him at all. The moment they came to the flash's attention, they'd get punched into space.