WarioWare Inc. MegaMicrotransaction$
Cost = Free
Wario games = Free
Jimmy games = 99 cents
Dribble and Spitz games = 99 cents
Mona games = 99 cents
9-Volt games = 99 cents
Orbulon games = 99 cents
Dr. Crygor games = 99 cents
Kat and Ana games = 99 cents
etc.
I don't think they should just dump their old ROMs onto iPhones (especially not GBA games, Jesus), but there is room for some franchises that fit into the whole microtransactions system, like WarioWare. I can't see people spending $40 for a WarioWare game in this day and age.
Alternatively, they can throw small minigames on the app store. Remember the minigames from Mario 64 DS?
how about the Pikachu surfing game from Pokemon Yellow?
Little shit like that would be fine, I think. Just to get the characters/franchises out there.
As for FULL old games, if ANYTHING, it should be stuff like Donkey Kong (arcade) or Mario Bros. (arcade). I don't think it's wise to just throw NES games and other games from Virtual Console onto the app store... you wanna tease the consumer with these small games. If they want the real shit, pick up a 3DS/Wii U.