I'm not really concerned over the Capcom side, as long as they have Captain Commando but Marvel side is a different matter.
They need the entire Fantastic Four, FF allies like Silver Surfer, Crystal (and maybe other Inhumans), villains well they have 2 already and decent too at that.
A fair whack of X-men (Nightcrawler without a doubt), no Emma Frost but definitely Jean Grey. No Marrow, she hasn't even appeared in a comic in ages and is currently powerless. No Omega Red, cool in the 90s is not cool now. Fantomex maybe, he's cool. Villains of Apocalypse, Sinister maybe, Magneto obviously, some lesser ones, like Sabretooth (for Wolverine) and maybe Toad and Mystique.
Avengers wise, well as many as they can, they have a good lot already (main ones) just need ... well actually that might do, Thor, Ironman and Cap are pretty much the Avengers. Throw in Hawkeye to fill it out...poor Avengers, they might be might but they sure ain't popular.
DareDevil should be in, Punisher too, Maybe Luke Cage and Iron Fist.
Oh Gladiator for the Imperial Guard and Nova.
Black Panther.
Black Knight.
Green Goblyn. Doctor Octopus.
... I could go on, some character just don't work though, like Quicksilver.
Hmm, pie.
