don't take this list too seriously, this game is rather new, and tiers are very subject to changeThis is not a SUPER official tier list, but it is a Japanese one they are using for now.
A Tier:
(Top) Sheik, Yoshi, Rosalina
(Bottom) Greninja, Zero Suit Samus
B Tier:
(Top) Bowser, Lucario
(Middle) Sonic, Fox, Wario
(Bottom) Duck Hunt Duo
C Tier:
(Top) Captain Falcon, Diddy Kong, Pit, Dark Pit, Little Mac
(Middle) Pac-Man, Peach, Villager
(Bottom) Bowser Jr., Mario, Meta Knight
D Tier:
(Top) Toon Link, Pikachu, Marth, Donkey Kong, R.O.B.
(Middle) King Dedede, Dr. Mario, Charizard, Mr. Game & Watch, Lucina, Jigglypuff, Olimar, Mega Man, Robin
(Bottom) Link, Zelda, Falco, Ness
E Tier:
(Top) Samus, Wii Fit Trainer, Luigi, Kirby, Ike, Shulk
(Bottom) Ganondorf, Palutena
it's also worth noting that the guys that made this list also said that the tiers are "much closer this time around"
a C tier could easily win a tourney according to them, and I agree on that. this game feels pretty balanced compared to other smash games