Last night I managed to finish Classic mode on Super Smash Brother Brawl with all characters. The challenges are tricky, because you don't just have to finish the mode with each character displayed on the character screen; you also have to complete it with their alter egos. This is the case for Samus with and without suit, Zelda and Shiek, and each of the Pokemon Trainer's trio. But I finished them all off, with a couple challenge unlocks as a result.
I have very few challenges left to obtain, maybe 10 remaining. There are still some that may be above me; I hope I have sufficient Golden Hammers!