character ability

S tier - metagame defining characters: Fox, Marth, Sheik

Characters defined by a lack of losing matchups*; effectively even matchups amongst each other and beat everyone below them. All 3 of these characters *could* lose to anyone in top 2 tiers but are strongly unlikely to.

#1 Fox - Only character I think he's more likely than not to lose to is Marth. Has a near even but still advantageous matchup with Sheik and beats everyone else. Outplaces Marth on the list due to being easier, more reliable, and winning matchups below this tier by a wider margin.
#2 Marth - Right now, I think Fox and Sheik are Marth's two "worst matchups" and he probably has advantages in both. Could turn out wrong though. Struggles with matchup knowledge related issues and is less reliable than Fox.
#3 Sheik - Breaks the primary rule by having a losing matchup (ICs) but is too good to be in the 2nd tier due to Fox matchup and severity of advantage vs everyone below. Also just a hella good character in a vacuum. Easily the most reliable character in this tier.

S- tier - flawed top-tier characters: Falco, Falcon, Puff

Characters that lose to every tier 1 character but have effectively even matchups amongst each other and beat everyone below them. All characters in this tier have lots of extremist qualities which are a big part of why they're in tier 2.

#4 Falco - best, most intuitive, and easiest MU against Fox out of the 3. Very straightforward character and doesn't have to change much between matchups except for obvious things like comboing floaties vs fastfallers. Suffers from fragility which leads to unreliability, but has godlike framedata and other powerful features.
#5 Falcon - Matchups are very hard to tell with Falcon, and could change depending on what is humanly achievable. Terrible framedata with broken movement creates extremist nature which leads to huge difficulty and unreliable nature. Requires tons of precision to make shitty framedata work, but makes up for that with potential MU spread.
#6 Puff - has weird MUs vs Marth and Sheik, but still likely loses to both to varying degrees. 6-4 at worst MU vs Fox (worst in this tier) but making it that close is really difficult. Very weird character with super strong punishes but in the end probably doesn't have a very good MU spread.

A tier - Gatekeeper characters: Peach, ICs, Samus, Pikachu

Characters defined by having at least one barely winnable MU in top 3 tiers but wins hard vs everyone below.

#7 Peach - Loses hard to everyone in tiers 1 and 2 except Falco who she still loses to (though has a much simpler side of the matchup). Peach is the gatekeeper of melee in many ways, all of which are because of punish game skews (also kind of broken projectile and CC game). Peach gatekeeps the top-tier because she loses to everyone above her but obliterates everyone below. Most characters below tier 3 have unwinnable MUs vs her. Peach gatekeeps high level players by seriously degenerating mid-level play with poorly designed risk-reward ratios and overly powerful panic buttons. Peach gatekeeps higher level players by being the most difficult character in the game to upset due to disparity in punish game. Puff MU might not be worth playing.
#8 ICs - secret low-tier destroyer; blizzard is unbeatable by everyone below them on this list (though Samus can get around it decently in practice). Loses to everyone above them but is one of the worst MUs for all below. Incredible degeneration of mid-level play because of infinite. Automatically wins vs lack of MU knowledge and understanding of how to deal w/ puppet character w/ grab infinite. Unwinnable MUs vs Peach, Fox, and Falcon, though the latter two have to exert effort.
#9 Samus - unwinnable Sheik and Puff MUs and very bad vs everyone else. Capitalizes hard off of slight misspacings/imperfect play and beats characters below tier 3 as hard or harder than Peach. CC game and inability to be punished can't be overcome by certain characters.
#10 Pikachu - Objectively should be in tier 4 but is much better at overcoming bad MUs than Yoshi/Luigi due to dashdance giving him better PvP capabilities to win bad MUs. Loses hard to everyone above him except Marth, which he still loses.

B tier - Almost good characters: Yoshi, Luigi

destroys everyone below but doesn't do that great above.

#11 Yoshi - Loses to everyone really bad but is weird and stupid. Weirdly decent MUs vs Falco and Sheik but still loses. Huge bad character destroyer.
#12 Luigi - Same as Yoshi, but loses hard to Sheik and Falco. Better at gimmicking though and speed makes terrible MUs more possible to overcome.

C tier - Worst usable characters: Doc, YLink, Mario, Pichu, Roy, GW

has at least one really big flaw but other workable strengths.

#13 Doc - shitty threatening range but can punish hard. Good CC game. Unwinnable Peach and Falcon MUs. Loses very hard to everyone else above him except Pika. Has memes.
#14 YLink - really fast and can camp very well. Loses hard to fastfallers who he can't punish and fast characters who he can't escape and hide his shitty framedata from. Has trouble killing characters that don't fall into bomb -> dair. Unwinnable Fox, Sheik, and Falcon MUs, potentially decent floaty matchups. Completely unknown Marth MU.
#15 Mario - Doc except can't kill shit but is better vs Sheik and Falcon and has better framedata.
#16 Pichu - very fast and can overcome bad matchups with that. Good fastfaller punish game, but very unwinnable floaty MUs. Tiny hurtboxes make it very hard for some characters to punish him.
#17 Roy - Has a dashdance, a poke, and a grab; automatically makes him better than everyone below him. Unwinnable floaty MUs. Can keep up with most top-tiers though.
#18 GW - decent moves, terrible defense. Can't beat Sheik, Peach, Fox. Worst character with usable hustle moves.

F tier - Best unusable characters: Ganon, DK, Link, Mewtwo

Framedata, mobility, and/or hurtboxes are too bad to play neutral. Probably has a decent punish game.

#19 Ganon - Works vs drunk people, new players, and people who get tilted over things that aren't an actual threat. otherwise has MUs where the other character can stuff his entire neutral game on reaction (sheik). unwinnable MUs vs Sheik, Fox, Falcon, Peach.
#20 DK - Decent movement, a few fast-ish hitboxes. Really good punish game on top-tier characters. Unfortunately has 0 threat when facing you, has 100% shitboxes, and is fucking huge. Unwinnable Sheik, Falcon, and Peach matchups.
#21 Link - Very big, combo food for every character, terrible framedata, surprisingly bad hitboxes. 2nd slowest character in the game. Has no way to cause knockdown until very high percents. Potentially winnable Puff matchup, definitely unwinnable Sheik, Marth, Fox, Falcon, and Peach MUs.
#22 Mewtwo - Allegedly decent vs Peach, which has been demonstrated. Otherwise very bad hitboxes, loses badly to CC and can't beat characters when they jump. Unwinnable matchups vs everyone except Peach and maybe Puff.

F- tier - useless characters: Ness, Kirby, Zelda

Multiple completely useless aspects. Has (very transparent) gimmicks.

#23 Ness - Terrible threatening range, bad floaty punish game. Unwinnable Sheik and Peach matchups. Weird disjoints make him work in some matchups though.
#24 Kirby - oddly okay neutral game in some areas, but has terrible mobility and shit punishes. Can gimmick Falcon hard and can force Sheik/Marth to play the game against him. Unwinnable MUs vs everyone else, especially floaties.
#25 Zelda - can kick things but is the slowest character in the game. Weirdly good Peach matchup.

Z tier - Fuck: Bowser

fuckin woops

#26 Bowser - literally not a single useful thing.