Marvel/MLP crossover

I'm sure this has been done already. However I plan taking these seriously. Don't know if I should make them all one shots and have different or one long story of vignettes. I am leaning towards one long story of vignettes due to the fact that they are related but at the same time they aren't since its one on one (ie only Fluttershy meets Bruce Banner). Also for my viewers I would like to see some insight on which Marvel character should meet which pony. Here are the line ups so far:

Fluttershy: Hulk/Bruce Banner

Rarity: Iron Man

Pinkie Pie:

Applejack: Captain America

Twilight Sparkle: Doctor Strange

Rainbow Dash:

Any ideas are welcome. All of them except Hulk/Bruce Banner meeting with Fluttershy are subject to change as well.