My older brother and I took to some cooperative gameplay, playing the main solo mode together, where you play as your Mii. Here, you compete in various events through progressively more difficult qualifiers, semifinals, and finals in hopes of gaining medals. Along the way, there are special challengers that desire to take you on, and beating them enables them for play in that event you beat them in.
This game is a blast in co-op, or at least with someone to play with. If you don't have anyone local to play with, Mario & Sonic's latest isn't right for you at full retail. Wait till it comes down in price, especially if you are curious in trying the game. A special incentive is that all of the games utilize button controls instead of motion controls of all the past console Mario & Sonic entries. I hope to post some screenshots in the next couple days.