personally I play any combination of Magneto,Hsen-Ko,Morrigan,Spencer,Dr.Doom,Iron Man, Tron Bonne, and Dr.Strange(rarely ghost rider too), And usually with each(with the exception of Iron Man,Tron Bonne,and Strange) I play with their DLC costumes...
Yes, Even Magneto.
Yes, you can pick it even though it was never released.
Maybe ill reveal how to do it.
If you really wanna know, all you need is anyone else's DLC. Pick Character A,whom has DLC,then go to Magneto. Deselect Character A by hitting B(xbox)/O(ps3),so your at the select assist type. Hit B/O again then hit LB/L1(Xbox and PS3 respectivly), about half a second later. If youve done it quick enough youll be on Magneto with Color ALT. Your welcome.