Basically I expect the roster to at least be this:
Row 1: Mario, Luigi, Peach, Bowser, Yoshi, Rosalina, Bowser Jr, Wario, Game and Watch (9 characters)
Row 2: DK, Diddy Kong, Link, Zelda, Shiek, Ganondorf, T. Link, Samus, ZSS (9 characters)
Row 3: Pit, Palutena, Marth, Ike, Robin, Kirby, Dedede, Meta Knight, Little Mac (9 characters)
Row 4: Fox, Falco, Wolf, Pikachu, Charizard, Lucario, Jigglypuff, Greninja, Another Pokemon (probably Mewtwo) (9 characters)
Row 5: Duck Hunt, ROB, Ness, Captain Falcon, Villager, Olimar, Wii Fit Trainer (7 characters)
Row 6: Dr. Mario, Dark Pit, Lucina, Shulk, Pac-Man, Mega Man, Sonic (7 characters)
And possibly this:
Row 1: Mario, Luigi, Peach, Bowser, Yoshi, Rosalina, Bowser Jr, Wario, Game and Watch (9 characters)
Row 2: DK, Diddy Kong, Link, Zelda, Shiek, Ganondorf, T. Link, Samus, ZSS (9 characters)
Row 3: Pit, Palutena, Marth, Ike, Robin, Kirby, Dedede, Meta Knight, Little Mac (9 characters)
Row 4: Fox, Falco, Wolf, Pikachu, Charizard, Lucario, Jigglypuff, Greninja, Another Pokemon (probably Mewtwo) (9 characters)
Row 5: Duck Hunt, ROB, Ice Climbers, Ness, Captain Falcon, Villager, Olimar, Wii Fit Trainer, Chorus Men (9 characters)
Row 6: Dr. Mario, Dark Pit, Lucina, Shulk, Pac-Man, Mega Man, Sonic (7 characters)
I would make a visual representation of this if I was a bit better with photoshop.