This is the current revision of the official tier list created by the Smash Back Room, ranking each character in SSB4 from best to worst based on votes from over 53 professionals at said game, current as of version 1.1.7. Please note this list doesn't account character customization, due to their collective ban post EVO 2015 in competitive play. Also, please note that Mii Fighters were excluded entirely from the tier list due to a large stagnation of data on them, and their legality being pretty shaky. Finally, Pit and Dark Pit were voted on as the same character due to them being almost entirely the same in every aspect.
Also, it is important to note that you should not let this be the deciding factor in whether you main a particular character or not. Of course, a character's individual standing is an important factor-it always is-but in the end, the deciding factor on whether you choose to main a character or not should be how you personally feel playing that character and how much fun you have playing with him/her. Now, on with the rankings!'
S Tier (You define the meta. Go you!)
1: Bayonetta:
2: Cloud:
3: Diddy Kong:
A Tier (Amazing, but not the ones)
4: Sheik
5: Rosalina and Luma:
6: Zero Suit Samus:
7-8: Fox/Sonic:
9: Mario:
10: Mewtwo:
11-12: Marth/Ryu:
B Tier (Can do pretty well if given the chance)
13: Corrin:
14: Lucina:
15: Pikachu:
16: Meta Knight:
17: Lucario
18: Green Mario (I mean, Luigi):
19: Captain Falcon:
20: Princess Peach:
C Tier (Pretty good)
21: Olimar:
22: Donkey Kong:
23: Toon Link:
24: Bowser:
25: Villager:
26: Greninja:
27: Mega Man:
28-29: Ness/Lucas:
D Tier (Average Joe central)
30: Duck Hunt Dog:
31: Link:
32-33: Pit/Dark Pit:
34: Yoshi:
35: Shulk:
36: R.O.B.:
37-38: Robin/Samus:
E Tier (Fine overall, but there exist better choices)
39: Mr. Game and Watch:
40: Ike:
41: Wario:
42: Roy (our boy):
43: Charizard:
44: Little Mac:
45: Palutena:
F Tier (Git Gud to win with these guys)
46: Pac-Man:
47: Falco:
48: Bowser Jr.:
49: Dr. Mario:
50: Kirby:
51: Wii Fit Trainer:
G Tier (Abandon hope, all ye who enter here)
52: King Dedede:
53-54: Ganondorf/Zelda:
55: Jigglypuff:
Unranked
Mii Brawler:
Mii Swordfighter:
Mii Gunner: