SPOILER ALERT
Every Character/Map leaked onto the web.
Returning Characters (Known from Dojo):
Mario
Donkey Kong
Link
Samus
Kirby
Fox
Pikachu
Zelda/Shiek
Peach
Yoshi
Ice Climbers
Bowser
Returning New Characters (Not posted on Dojo):
Marth
Game & Watch
Luigi
Falco
Ganondorf
Ness
Captain Falcon
Jigglypuff
Newcomers Known:
Diddy
Pit
Metaknight
Pokemon Trainer
Ike
Snake
Dedede
Olimar
Lucas
Sonic
Wario
Newly released Newcomers:
Lucario
Toon Link
R.O.B.
Star Wolf
Known Stages:
Battlefield (Original)
Battleship Halberd (Kirby Super Star)
Bridge of Eldin (The Legend of Zelda: Twilight Princess)
Castle Siege (Fire Emblem)
Delfino Plaza (Super Mario Sunshine)
Distant Planet (Pikmin)
Frigate Orpheon (Metroid Prime)
Lylat Cruise (Star Fox)
Mario Circuit (Mario Kart)
Mushroomy Kingdom (Super Mario Bros)
New Pork City (Mother 3)
Norfair (Metroid)
PictoChat (DS)
Pokémon Stadium 2 (Pokémon)
Rumble Falls (Donkey Kong: Jungle Beat)
Shadow Moses Island (Metal Gear Solid)
Skyworld (Kid Icarus)
Smashville (Animal Crossing)
The Summit (Ice Climber)
WarioWare (WarioWare)
Yoshi's Island (Yoshi's Island)
Brinstar (Metroid)
Corneria (Star Fox)
Onett (Earthbound)
Rainbow Ride (Super Mario 64)
Temple (Zelda II: The Adventure of Link)
Yoshi's Island (Yoshi's Island)
Stages Returning (Previously unannounced):
Big Blue
New stages (Unannounced):
Classic Mario Bros. Stage
Green Hill Zone
Tetra's Ship
Port Town
Mt. Coronet
Luigi's Mansion
Electroplankton Stage
For a full summary, visit: http://www.neogaf.com/forum/showthread.php?t=233454
END SPOILER