Well I gotta save some for the sequels!
Also, the good bom-bombs led by General White & Admiral Bobbery & the Bean Bean Kingdom (I would try to balance the good/bad ratio).
Mario RTS, an idea I've been tinkering on since the N64 days. The Wii's controls can really make it a great game.
There are a number of different factions that the player can command:
Mini-Mario Milita
The "good" faction. They're not quite as mini as the ones seen in past games, these are...