Oh and I've got an Idea for the style of the game, we could use these for the main characters:
Mario
[link]Luigi
[link]Peach
[link]Toad
[link]Yoshi
[link]Bowser
[link]And we could us tiles and bckgrounds from Super Mario World, Super Mario Bros 3 and Super Mario bros 2 Advance. They're on Spriters Resource