Here is a list of how to unlock characters. I’ll update it when I figure out how to unlock the last three. By the way, if you unlock them using the Subspace Emissary, you are a pansy. Schmucks.

All characters can be unlocked somehow through the Subspace Emissary.

Ness - Reflect ten projectiles - Play five VS matches

Marth - Beat Classic mode with any character - Play 10 VS matches

Luigi - Beat Classic mode with no continues - Play 22 VS matches

Falco - Beat 100 Man Melee - Play 50 VS matches

Captain Falcon - Beat Classic Mode on Normal in under 12 minutes - Play 70 VS Matches

Lucario - Beat Target Smash with one character on all difficulty levels - Play 100 VS Matches

R.O.B. - Get 250 different trophies and then play a match - Play 160 VS Matches

Mr. Game and Watch - Complete Target Smash on any single difficulty with 30 characters - Play 250 VS Matches

Sonic - Complete Classic mode on any difficulty with 10 characters - Play ??? VS Matches

Snake - Play 15 matches on Shadow Moses Island - Play ??? VS Matches

Jigglypuff - [If anyone knows the normal way to unlock, please tell me] - Play ??? VS Matches

Toon Link - [If anyone knows the normal way to unlock, please tell me] - Play ??? VS Matches

Wolf - [If anyone knows the normal way to unlock, please tell me] - Play ??? VS Matches