Monster High X Avengers (Marvel) AU
Frankie Stein = Thor (because of the electricity/lightning)
Cleo DeNile = Tony (Iron Man)
Ghoulia Yelps = The Vision/Pepper Pots (because he used to be Iron man's AI Jarvis. And pepper because Cleo can't get by without Ghoulia)
CA Cupid = Hawkeye (Bow and arrow)
Jackson Jekyll/Holt Hyde = Bruce/Hulk OR Moon-knight (I can't decide between the two!) Maybe Mystique?
Abbey Bominable = She- Hulk (or regular Hulk depends who JJ/HH is)
Deuce = Cyclops or War machine/Happy (so he can be closer to Cleo)
Toralei Stripe = Loki (mischief, plus she and Frankie have already been siblings in Scarily ever after)
Robecca Steam = Nebula (alternatively, The Vision)
Venus McFlytrap = Groot
Rochelle = Gamora/Mantis? OR Emma Frost (because she can turn herself Diamonds)
Spectra Vondergeist = Kitty Pryde (wall phasing)
Scarah Screams = Jean Grey (or any kind reader)
Wydowna Spider = Spider-man? (Maybe too obvious)
Heath burns = The Human Torch
Manny = The Thing
Invisi Billy = The Invisible Woman
...
(Let me know if this has been done before!)