Neo-Geo Forums

Well my friend and I just got through playing some Mario Kart DS through wifi and we had a blast. I really enjoyed it, but as fun as versus games are, I want to play some co-op games.

So my only question is, what are some good co-op games for the DS? I'm looking for something beyond what Castlevania DS offers. Maybe some sort of RPG or game we could play separately and then go online and use what we accomplished by ourselves together?

Oh yea, and it has to be a good game.