That is some awesome defense. I've only seen that myself on 1/20+ play-throughs of the game. I'd say 9 out of ten, with 10 being perfect level ups every time.
Shouldn't the Paper Mario series be under the Mario RPGs? As for the poll, I like the 3D Mario games the best. They're not to long and they have fun gameplay. The RPG games area close second.
Well GameStop defenetly won't take anything older then the GameCube games and even then they may not take the GameCube games either. I'd say try Amazon, Ebay, or Craigslist.
What GameCube games are you looking to sell?