I think Mario has some misconceptions and preconceived biases associated with him.
The major thing is this idea that his stats are "average," or that he's a solid character who is good at everything but not great at anything. This was true in previous smash games: Mario
was the everyman
; his stats
were perfectly average. But that's not the case in smash 4: airspeed is too big of a factor for it to be so (also his up-smash is amazing in this game and a dominant factor in his success). Mario was average when his airspeed was average and you could wall him out due to his limited range. But now the strategy of "just wall Mario out with hitboxes" doesn't quite work any more unless your name is Rosalina. Mario is not an everyman. He's an extreme. Extremely good at moving around and weaving and extremely good at combo'ing/stringing together hits, with extremely fast attacks (best average frame data in the game besides Luigi). Defensive options (besides airdodge to the ground) got much stronger going from Brawl to smash 4 (the
best airdodges/rolls in Brawl are now just about average for smash4), and for a low-range, high-mobility character like Mario that matters a lot and highlights his extreme traits.
I've seen several character boards start out saying early on in the game's lifetime that "Mario should be an easy or even matchup" and end up shifting to "Wow, Mario is actually really hard, I don't know why I'm struggling, in theory we should win." A great example of a misconception coming unraveled with time.
Mario has come a long way from when the game first came out. His punish/combo game has been optimized over time. He used to be only d-throw to up-tilt chains at low % but now Mario just lightly touches some characters and they take 30-60 damage from elaborate strings. f-air has become a legitimate combo tool (d-air -> f-air for instance). All of his aerials and tilts now have uses (except f-tilt I guess). KO'ing is not a problem in most matchups just because of his weight and how easy it is to land f-smash or up-smash (and how safe it is to throw out these moves) on landings/empty hop baits, which are once again enabled by his airspeed.
Additionally, Mario's toughest matchups were nerfed over time, and that too
in the way most beneficial to Mario. Mario lost hard to characters who didn't care so much about his weaving (because of decent weaving of their own) but had much higher reward/kill confirms: 1.0.4. Diddy, 1.0.6. (?) Sonic, 1.0.9 Luigi. But they were all nerfed, specifically in their KO power (which was the problem for Mario), and now at least two of these characters actually have some trouble vs. Mario (never mind Komorikiri vs. Ally for now) or at least consider him a "tougher end of" even matchup. If you take a look at the set that 6wx took off of Ally at Shots Fired, you'll notice that most if not all of the KOs that Sonic got came from b-throw. With b-throw's nerf, 6wx has been losing to Ally consistently and it's usually because
Ally kills him first. Those kill power nerfs mattered a lot--Mario loves it when you let him play the Fishing For Rage Up-Smash game, and it shows in the results.
If you consider Mario's matchup spread in a vacuum you might not be impressed, but look at it in comparison to that of other characters and you'll see that it's actually one of the best in the game. He has the tools to succeed in even matchups that he theoretically loses and so it's difficult to say that Mario loses any matchup more than 45:55. For instance it's commonly agreed by Marios that Rosalina is his worst matchup but Mario has so many tools in this matchup that I've seen several Rosalinas claim that it's ether even or one of Rosalina's more difficult matchups. Just compare how Mario does vs. Rosalina to how Diddy does vs. Rosalina: Mario has a much easier time KOing thanks to up-smash, gets gimped a lot less because his up-b is so good, has b-throw and dash attack to get rid of Luma, and can instant-death Rosalina at any time using Cape if she flubs her recovery angle.
Every time I see Mario vs. Sheik it looks like an even matchup, except when it's Ally vs. ZeRo, but Ally seems much worse than Anti at avoiding Sheik's KO setups, especially out of d-throw, so I think this might be a player-specific problem. ZSS mains have claimed on their board before that Mario is one of their harder matchups (I've even seen
Shaya
say it's ZSS' hardest), so at the worst I can see an even matchup here, though the recent buffs may have turned the tides. Sonic is probably even or close to it (we don't know where the matchup actually lands in the range of values provided by Komorikiri for Sonic's matchups; it may be closer to 50:50 than 45:55 for all we know). I don't buy that Ryu is a bad matchup for Mario; I think Marios just need to stop up-smashing the falling focus attack (even d-smash with the double hit is a better choice). Ally was playing the MU vs. Trela significantly better than he played the MU vs. 9B even though 9B is probably the better Ryu. Ryu has one of the worst airdodges in the game, and he has trouble reversing his aerial momentum, so as long as Mario maximizes his punishes and plays a safe, almost campy game like Ally was doing against Trela in some of the matches then Mario should be fine.
Greninja is listed as a difficult matchup for Mario in
HeroMystic
's list, and I've thought the same before, but Greninja mains have often said that Mario wins due to his up-tilt chains/combos and weaving/pressure, so here's yet another example of how Mario's "worst MUs" are not actually bad MUs but probably just "annoyingly even with some properties that Mario doesn't like." Oh no. How horrible. Poor Mario. He actually has to
try.
Meanwhile if you take the MU spread of any other character besides Sheik (and perhaps postpatch ZSS) you'll find several difficult matchups. Sonic probably loses to ZSS, Sheik, and Rosalina at least, and Ike is looking like a hard MU as well. ZSS has some issues (historically) with Pikachu, Ness, Diddy, Mario (?), and Sheik, so that's at least 5. Rosalina struggles with ZSS and has troublesome Falcon, Pikachu, MK, Wario, and Marth (?) matchups at the least.
Then if you look at Mario's good matchups he is the hardest or 2nd hardest matchup for several characters: Pikachu, Wario, Megaman (paging
Locke 06
), Olimar (probably after Sheik), etc. I've seen Shaya suggest that Mario is one of Marth's worst matchups before the Marth buffs and
@san. suggest that Mario is Ike's hardest matchup before the Ike buffs. I've seen Fox (who is supposedly better than Mario) also struggle with Mario for what it's worth, though the matchup may be even regardless. Ally vs. Larry looked extremely difficult for Larry, at least.
Mario's matchup spread is pretty ridiculous and with tools like a frame 2 jab, frame 3 n-air, small size, medium weight, a b-throw that kills, strings, invincible up-smash, FLUDD, high mobility on the ground (initial dash) and in the air, a frame 4 jumpsquat, Cape, a projectile, and a hard-to-gimp up-b, there's no character in the game who can say that Mario is an "easy" matchup and several characters who can say that Mario is a hard matchup. On top of that, Mario has a healthy amount of representation and succeeds on numerous levels with players like Zenyou, Ally, Anti, etc.
I don't know about guaranteed top 5 because there are so many good characters floating around up there, but to say that Mario is not even in the running is a little extreme. There are solid arguments to be made in his favor.