Mario's tilts, throws and aerials are some of the best combo starters in the game, he has extremely good frame data, great edge guarding tools, and good tournament results to show for it. If he WAS nerfed, it clearly wasn't enough
None of his tilts combo as well as old dthrow, except dtilt at very magic percents/positioning.
His edgeguarding is actually trash. Because those tools are ONLY for edgeguarding.
Cape is slow, halts forward momentum, loses to disjoints, and mario's lack of reach offstage only makes it a threat after requirements are met. (Their recovery just being that bad, having sniped their jump, etc)
Literally any fair faster than frame ten (almost all of them) is more of a threat than cape.
And FLUDD is a better neutral and ledge trap tool than edgeguard except in very specific matchups, but even then; You need to meet several requirements before it's a threat usually.
His bair is a very linear hitbox, and being a bair on a short recovery char limits it's range of effect heavily. Unlike upward swoop bairs like Marth, Cloud, DK, Sonic, etc; It can't cover both jump, and fall. Again, largely requiring they be caught simply off guard, or have no jump. It's lack of strength, and poor angle also provide little reward until percents it just plain kills. So bair demands little respect.
As for results; Like I said, Mario is a mid-tier. He's not non-viable. And his results are pretty much in-line with a mid-tier, especially if you consider the ones getting results with have have been playing him for 3+ years. (And most of the better results are from the very start of the game)
I could be wrong. But like, most top players agree with me he's middish/low high tier. And every objective, observable measure also supports that theory. Only character specialists have been generating any sort of results with him.
This alone shows that you either have not spent enough time with Mario, aren't using him correctly at all, or just plain don't understand how to play Smash.
...How in the HELL are you gonna say he can't combo when he's easily in the top 3 most combo oriented characters in the game? That's like saying Olimar has trouble racking up %. His edgeguarding is fantastic with how fast bair is and how long nair lasts, and Fludd messes with quite a big chunk of the cast.
He has amazing frame data and ground/air movement, an absolutely *smothering* advantage state, *TWO* separate frame-3 OoS options, and only has 5-6 unfavorable matchups in the *entire game*. You can't tell me you've watched the likes of Dark Wizzy/Mastamario/Ally/Prodigy and still say he's a mid tier. Literally every list that has come out from every pro have put him solidly in high tier. He's a top 20-25 character in this game, and if you think otherwise you need to re-evaluate how you're approaching this game completely. He feels underwhelming to you because you have no idea how to use him, but don't blame the character.
I'm actually fairly confident I've played him more than you, at least. In both games. And I'd appreciate you not defaulting to knee-jerk claims of a lack of experience while I live in a major smash area with tournaments nearly every day of the week. (MD/VA)
And his combo game is fine. But hardly top 3. Like, what is he even comboing off that well? For that long? Even doctor mario has more consistent combos from all starters at more percents. More kill confirms too. That claim is just resoundingly false.
As for edgeguarding; No. It's not fantastic. For reasons I've explained above. But I understand how one might be confused considering his specific tools for edgeguarding in FLUDD/Cape. And it's far harder to prove or disprove just how good a character's edgeguarding is.
But In those players you listed, very rarely do they generate stocks from edgeguards against better players. You'll have to research this for yourself, but I'm confident you'll come to the same conclusion as me if done properly.
And 'literally every top player's lists have him high tier'? ZeRo has him in C, actually. So hardly 'literally every.' But yes, many have him hover around mid/high tier. And I never claimed they were very far off.
Again though, I could be wrong. But clearly not for the reasons contested here. They're more than palpably untrue, but you're welcome to see how the Mario Meta plays out for itself. If my claims become more obvious with time, but I'm afraid I won't be spending much more time in the Mario section to continue explaining my reasoning. So you'll have to be content with what I've provided so far.