Mario (Dr. Mario as an alt, composite moveset that gives him the best traits of both), Luigi, Wario, Peach, Rosalina, Bowser, Bowser Jr (unlockable, Koopalings as alts), Donkey Kong, Diddy Kong, Yoshi
Kirby, Meta Knight, Dedede, Samus, Zero Suit Samus, Pikachu, Jigglypuff (unlockable), Mewtwo (unlockable), Charizard, Lucario (unlockable), Mimikyu (new)
Fox, Falco (unlockable), Captain Falcon, Ness (unlockable), Pit (Dark Pit as an alt, composite moveset that gives him the best traits of both), Palutena, Link (BotW appearance, new moveset that incorporates elements from the game, has OoT outfit as an alt), Zelda (BotW appearance, mostly the same moveset but uses the Bow of Light more in her moveset, has OoT outfit as an alt), Ganondorf (unlockable, a theoretical BotW design, similarly to how Sheik in Brawl, how she would have looked in TP, OoT outfit as an alt), Sheik (BotW Sheikah clothing, OoT outfit as an alt), Toon Link (MM Young Link as an alt)
Marth (Lucina as an alt, composite moveset, as strong as Lucina normally but keeping the tipper), Roy (unlockable), Ike, Robin, FE16 rep, Mr. Game and Watch (unlockable), ROB, Duck Hunt, Little Mac (unlockable), Olimar (unlockable)
Villager (unlockable), Isabelle (new), Shulk (unlockable), Squid Kids (new), ARMS rep (new)
Greninja won't make the cut as it lacks relevance now
Corrin is dropped, he lacks relevance now, and was just there to promote Fates
Wii Fit Trainer and Mii Fighters represent a dead brand, so they are cut
Lucas is on the verge, but I think he should be cut, since Mother 3 coming here at all is a meme, while Mewtwo and Roy continue to make appearances in their franchises and were also Melee veterans
The third parties are completely up in the air, Sonic, Ryu, Cloud, Mega Man, Pac Man, and Bayonetta
Bayonetta has a good chance of returning since I think Bayo 3 is coming up on the Switch?