There are 11: Luigi Dr. Mario Young Link Ganondorf Mewtwo Jigglypuff Pichu Falco Lombardi Marth Roy Mr. Game and Watch
Unlock all the characters and etc.
I only know a few which are Mewtwo , Pichu , and... that's all i can name. Sorry .
Yes, 11 characters are hidden.
Here is how to get all the secret stages: Beat event mode 50 and 51, Beat classic mode and adventure mode and all star mode with all characters and unlock all characters, Beat all the multi man melee modes, Hit Sandbag in home run contest with 1 character 2,000 feet, Collect the birdo and pidgit trophy, Finish target test with all characters, Play 1,000 melee's in melee mode (no special melee's), Complete all the events in event match.
Play 1,000 melee matches in melee mode or beat classic mode with mewtwo after unlocking the other secret characters.
Unlock all the characters of super smash bros melee
Finish all the events before it then unlock some of the secret characters more events will appear.
awtewtrsrese
Get all the characters, Play 500 melee's, Finish target test with all characters, Get 2,000 ft in home-run contest, Finish 15 minute melee in multi man melee mode, Finish all the event matches, Get the birdo and pidgit trophy.
u forward it and get it
About 25 characters Sonic is not really on there. That's all.
Keep working through the subspace essimary and you'll get characters as you go