PERSONAL OPINION TIER LIST TIME
Each individual character isn't ordered within the tiers, only the tiers themselves. Alternative ranking for tiers by comparison is S, A+, A, B, B+, C, D, and F
I'll give my opinion on a few characters in particular with this
--------------Top-------------
I don't get the impression that any of these four have significant weaknesses. Maybe small things.
Rocketbarrel Boost is error-prone and sometimes exploitable but between the angles and Monkey Flip, Diddy has a pretty diverse recovery to make up for it. Besides that, he's dumb. Really, really dumb. He has grab combos, airdodge read Uair kills at high %s, edgeguarding with Fair, mixup options you'll see like Nair and Dair, kill throws at the ledge at high %s, killconfirms with Dtilt and Banana, etc. Main balancing factor imo is that most of his kills come at 110%-130%, but that's not enough to stave him off from being the best character.
Sheik could also be the best. Pros have her MU spread better than Diddy's, with Diddy mains (as far as I can see) generally considering a few odd, rare MUs to be losing. However, while Sheik is a demonstrably consistent character, since the nerfs, she hasn't taken any major event where a large number of top players were in attendance, even as her tech has developed. This could be the limitations of Mr. R or VoiD showing itself, or Sheik's followup for massive % game > find a kill doesn't suit itself quite as well as Diddy's does since the latter has simpler and plainly better kill confirms.
It's weird going from Melee and Brawl's "No losing MUs = top" but I don't think Diddy loses any matchups on a significant enough level for it to seriously affect his bracket presence, and past that, in the hands of a neutral master, I feel like he's just the better character. Cloud was considered shaky for a while as a MU but top level record seems to suggest it's pretty even.
Bayonetta looks gr8 as of late. Long-term trends have stabilized her after her drop-off post nerfs, and her best results came
after said nerfs. Good damage building and maximizing Witch Time punishes are a game changer. Salem rarely ever messes up punishes now whereas you'd see Tyroy, Riot, Fresh, and other top Bayos either never utilize it enough or fail a lot at maximizing returns on a successful Witch Time hit. Consider it can go as far as being an entire stock if maximized enough, that's probably one reason she's stabilized and is such a pertinent meta threat.
I think Sonic could be top 3. MU spreads from top players all indicate a top level threat, and we've seen a perfected Sonic playstyle (e.g. changing playstyle per the situation) at the hands of players like KEN and Komorikiri who have a few recent sets on top-level players with Sonic. I can't think of any weaknesses the character has. Good multi-purpose Up B, insane speed between his running speed and Spin Dash, good grab game backed up by great ground mobility, ability to time out with his mobility if the situation calls for it, etc. Extremely pressuring character to deal with if fully utilized.
--------------------High----------------------
Cloud has really good placements at the regional level as of late and is by far the best secondary pick in the hands of a skilled player, but solo winning placements are comically rare and entirely nonexistent at the top level. Close calls have happened with Tweek, M2K, Ned, etc, but they all tend to get denied. Having a bad Bayonetta matchup where she can fully reap the benefits of Witch Time with minimal effort makes his life hard even if he's great at building damage and doesn't have a lot of trouble killing. His recovery isn't as bad as people make it out to be since his double jump is gr8, but it's a pretty big weakness. If we judge him by solo, I think he's on the low end of these 10 characters.
R&L is dangerous, but matchups against disjoint-carrying characters leads to Luma dying earlier, which is only exacerbated by the existence of characters like Cloud, and worsened by the rise of characters like Marth, or the slow second-rise of old favorites like Meta Knight. Even if she doesn't lose the former two MUs (I assume both are debatable?), good spacing & disjoints seem like serious trouble for the character. Hence the high-tier instead of "top".
Ranai, ScAtt, and Kamemushi have also demonstrated that projectile heavy characters can totally contend with RosaLuma at a high level, meaning she's not quite as oppressive towards certain character subtypes as she could be. Ness MU seems pretty hopeless but that's because his recovery is reliant on a projectile, so it's not a matter of greater-than-man-can-achieve patience like it is with Villager vs. Rosa.
Mewtwo is closest to being #5 among these imo. Stupid character with a dumb grab, dumb fair, dumb projectile, dumb footstool kill, dumb everything. hatehatehate
----------------------------Upper-------------------------------
All of these imo are at the cusp of high-tier. I could see Marth moving there in the future since he just appears to get better and better as a defensive character as time goes on, with MKLeo's set on Ally being a big breakthrough in particular.
I'm tentatively putting Lucina here. I think the takeaway from the character is that she's totally viable but few people will play her seriously since she's just a Marth that doesn't reap rewards as well. Might be overestimating her since Tippers assuredly make a big difference in certain MUs but she's probably either High or High-Mid, in the A-B Grade range.
----------------------High Mid------------------------
I've been a Lucario skeptic for a long time. His results are subpar and his mains are
notably inconsistent. I think his neutral is bad and he almost totally relies on comeback gimmicks, lone strings that equalize the playing field enough that he can snap somebody off with aura-charged aerials, etc. He can have good runs but he'll never win a major and his luck will eventually run out if he keeps running into players with really precise neutral games that outplay him. The keyword here is he "can" jank, and has (ZeRo died at 30% in his match at Day to an Up Smash, according to a spectator on Reddit) but this is an anomaly that the bad design behind the character allowed, not a game-by-game trend. He needs game-by-game trends like that, in my opinion, to be higher on the list.
I'm not sure on Ness/Lucas. Both feel like they hover in the same place. Both have strong grab games but I feel like Lucas' stronger recovery might make him more formidable long-term, and spaced PK Fire is gr8. Both have kill throws but Ness' Bair is unmatched afaik. I think Shaky and FOW's runs at Genesis 4 will give an answer of where this character stands long term but I could see Lucas maintaining this position while Ness drops. Lucas has more to his name recently, at the very least.
---------------------------------Mid------------------------------------
**** ROB. 20BeepBeep sux. Skynet sux. No competent robot rebellion can be upended by Gyro getting grabbed and proper DI stifling your grab combo. For real, though, I think he's a decent mid-tier but MU knowledge tanks him super hard. His kit isn't awful but he really gets hurt without the one-two Laser/Gyro hit to build extra damage and keep the opponent spaced.
Grapplers (Bowser & DK) are good but inconsistent since they rely on grabs and can cheese you one game but get destroyed the next. That's often referred to as bad game design, but admittedly, in a movement-based game that naturally favors speed... it's hard to make heavyweights work since they're naturally slower, meaning you need to add gimmicks or cheap kills to their arsenal to equalize them with the rest of the cast.
I'm not convinced Yoshi is good. No hype that's ever built up around his mains ever amounts to anything, it doesn't feel like he has a gameplan and he just has a bunch of variously decent-but-disconnected tools that don't lead into each other or form a good flowchart, etc. I may have commented on this before and had a response after Yoshidora got 17th at a Japanese tourney, not sure.
-------------------------Low Mid----------------------------
I'm meshing this as best I can, but it feels a lot cleaner than it did so many months ago when I tried to separate the mid-tier swamp of "maybe they're good" characters. Pac, Wario, and Ike all have demonstrated decline. WFT, G&W, and Mac are notable stagnant, long being considered low-to-lower mid tier.
I think Link and Duck Hunt has leveled up, and as a potential future Link user, I'd like to believe he can rise as a character - it feels like he has the most potential of any character in this category (and opinions on him are all over the place) - but I'm holding him here for now, especially after T's recent bombs.
Opinion on trajectory, since I feel like "Lower Mid" is basically a Borderline tier that most characters will move upwards/downward from:
WFT - Stagnant, likely has found her niche as a lower mid tier character, maybe top of low if John Numbers starts bombing or goes Corrin most of the time.
Wario, Pac-Man, Little Mac - Downwards. Mac has been stagnant but his continual lack of breakthrough makes me think his mains will eventually start dropping him. He's been on that edge of making a major accomplishment, but it never really happens, and he's confined to a regional level and seems like a lock for an inconsistent-type that can just lose if he's put in a bad situation that most characters would survive.
Link, Duck Hunt, Mr. Game & Watch - Upwards(?). Duck Hunt has a lot going for him, but I don't know if it's a lot of gimmickry that's increasingly been figured out in Japan. Duck Hunts don't place as well as they used too (though you had a recent good run) which makes me wonder if DH is doomed to stagnate or decline. G4 might answer some questions on this.
Mr. Game & Watch almost seems like a good character. I'd like any resident G&Ws to comment on him, actually, because seeing Regi's play makes me wonder why more people haven't picked the character up. Any major disadvantages that really bomb the character?
------------------------------Low-----------------------------------------
I think all of these characters will have randomly good performances and niches but none of them will aspire much higher than that. Palutena looked good for a while, but nothing came of it, and the other characters here are stuck in Low Tier hell with little to their names beyond one-hit-wonders. BJ declined to this point, Shulk hasn't had the breakout moment his mains have wanted forever, I forget Kirby even exists, etc.
Roy feels like he might be on the cusp of something, with HyperKirby's GA performance and Ryo's performance with Roy, but I think that might file under the "one-hit-wonder" category, especially if we don't see repeats of it in the future. He's probably the only character at this point that could go higher at some point imo. Maybe Samus, too? I want IcyMist to attend more stuff.
-----------------------Bottom--------------------------
As somebody who used to use Falco a lot I might just be pessimistic but I don't think his Bair or Uthrow combos salvage him. His mobility is awful and he just can't do much of anything. Constantly feels like he needs to get hard reads to kill, his recovery being mediocre isn't justified due to him not having the same amount of pressure-building Fox does... etc. Anragon's MU chart is also horrible looking for him as a character. Using this tier list, 7/10 of the top characters are in the "significant disadvantage" or "disadvantage" equivalent lists:
This would imply that his only Even or better MUs exist as high as mid-tier... that's particularly bad if accurate, and little has materialized to make me believe anything else. Even AC seems to liberally use secondaries. Our resident Falco guy can chime in on this I guess. I think the other characters here are too bad for him to be bottom 5 but I think he's bottom 10 for sure.
I think Ganondorf may be the worst character. I remember discussions of how power-shield heavy Ganondorf is totally not that bad, but the character has so little to his name after nearly two years - it's just a character that feels like he has no gameplan beyond applying basic fundamentals and hoping his reads work out while being saddled with an actually bad recovery and bad mobility.
Rest are just bad for endlessly discussed reasons. None of them are and ever will be tournament viable outside of incidental regional placements. Barring major buffs with a possible Switch port, you will never, ever, ever see a D3, Zelda, Ganondorf, etc. placing very well with main-with-secondary/solo at a major. Ever. It's like trying to main Roy in Melee.