My PSP design comp was dropped real fast, so I decided to host a competition, where you make a box, and it has to have Mario and Sonic on it, no existing games (Olympic Games, Brawl, etc.) and it has to be Next Gen (DS, 360, Wii, etc.)
I can add more if necessary.
To be even MOAr specific, you have to do something that people would actually buy, no card games or such. You can make something like a Mario and Sonic Tennis game, or even a SSBB sequel (Go ahead, see where you get.)