Basically, I make a random list of characters, and everyone tries to put them into groups - a group containing 2+ characters who share something in common.
Here's the list:
Sora Takenouchi (esp. season 1)
Miyako "Yolei" Inoue
Misty (from Pokemon)
Coco Bandicoot (From several of the Crash games)
Momo (from Breath of Fire 3)
For 'expert mode' I suppose you could, if there end up being several main groups, you could attempt to find other characters who fit into several (3+ maybe?) of them.
Yes, I am truly bored.