Applejack is Steve.
Rainbow Dash is either Thor or Tony. (I felt she could almost go either way, and look how well all these pictures go together!)
Fluttershy is Bruce. (Look at them! They're both soooo cute!!)
I might have a tiny crush on Mark Ruffulo.
And Celestia is totally Nick Fury. It's just obvious. Lots of secrets, having the mane six do all the fighting.
Finally, here's a picture of Tony in a shirt that I know we all wish we had, and a picture of the adorable Matt Smith hugging a purple unicorn pillow pet. <3 They all so adorbes.
Also, I'd like to remind everyone that Benedict Cumberbatch and Tom Hiddleston's friendship name is Cuddles. That is all. Carry on.