To me, I think the whole "unstoppable when played at absolute perfection" argument is very flawed.
If we are analyzing characters played at about equal skill levels, then we should assume that the opposing character is also played at the absolute perfection. Whenever people put in the argument of the "played at absolute perfection without any flaws" to argue in favor of a character's viability (i.e. Ultimate Pika), they always tend to focus on the character they are arguing for and disregard what would happen if the opponent is also played at absolute perfection. As NotLiquid mentioned, Shulk's entire existence in Smash Bros is built off of potential theorycrafting, assuming perfect play.
Either way, reaching levels of being played at absolute perfection is very unrealistic and gets written off as extreme theorycrafting.
At best, it only lays ground-work for future developments of the character, although at this point, it is basic theorycrafting.
Funny that this list was posted, as it does bring up a topic I was thinking of posting earlier today, specifically the topic of
.
In Mr. R's tier list, he places Marth as the 10th worst character. I am not sure if his mid tier is ordered (I think it is), but even in the region where Chroy and Lucina are running wild, Marth is viewed rather lowly. Although Mr. R's list wasn't really going to change my opinion on this anyways, but after playing and watching Marth for quite a while recently, but the more I begin to realize how very rough Marth has it in this game.
It is not just because it is harder to land his tippers in this game, between many of his setups to land tippers being made either way harder to land or outright removed, and the lack of any microspacing options available (perfect pivoting being removed).
While Marth's unreliability to land tippers in this game plays a huge part on his drop in viability in comparison to his past appearances, his large drop in viability isn't just associated with that. This is merely only one part to an even greater nerf Marth has received in the transition from SSB4 to Ultimate.
Some of his most reliable KO moves go their knockback worsened, particularly on sourspotted moves. The sourspotted hitboxes of forward smash, down smash (back hit), and Dancing Blade got noticeably nerfed, as well as tippered forward air, and the upward variants of Dancing Blade lost pretty much all of its KO power. In SSB4, non-tippered forward smash would be able to KO midweights under 100% at the ledge. Tippered forward air would sometimes outright steal games, especially with rage. Up throw knockback nerf and Dolphin Slash landing lag nerf certainty doesn't help much, as he arguably relied more on both of those moves than Lucina did in SSB4.
This leads to a very unfortunate situation for Marth.
It is now much harder to land tippers given both the indirect and direct nerfs given to him, but also thanks to the nerfs to the knockback of some of his moves, it further necessitates that he must lands tippers. The more aggressive nature of the game combined with forward air's range nerf is also a blow to his general defensive playstyle.
Given this and the fact that his sourspotted moves continue to hit like a wet noodle (+ Dancing Blade damage nerfs), the end result is that Marth just plain feels very unrewarding to play. You may have that one moment where you go on a tipper spree, but moments like that is very uncommon.
Even in comparison to not just Lucina, but some of the mid tier swordies like Byleth, Robin, Corrin, TLink, etc. Marth feels very unrewarding for all the effort you must put in to make him work.
He feels like a watered-down version of his SSB4 self, trapped in Ultimate's engine. This is, in an ironic twist, the reverse of Roy. SSB4 Roy feels like a watered-down version of his Ultimate self, trapped in SSB4's engine.
We all see MkLeo have splashes of success with the character, but out of all the characters in his back-pocket, he has the most trouble making this character work. Even Byleth, a character people typically don't view all that fondly (at least back then), was put in much more work.
Patch 8.0 did help a little by making tipper forward, back, and up aerials easier to land, which helps out considering that forward and back air hitboxes were altered in the initial transition to make tippers harder to land. However, it didn't seem to have much of an impact on his tournament success. Making them easier to land helps, but it didn't really do too much to fix his core problems.
If they are going to fix him in this game, there are two solutions that come in mind that they could do. They could do both.
The main one is to make landing his sourspot hitboxes more rewarding in both damage and knockback, so Marth doesn't feel constantly burdened with landing tippers all the time.
The other is to offer Marth some new
reliable setups to tipper KOs, like with SSB4 Dancing Blade and jab.
Either way, I don't think simply making tippers easier to land raw is going to be the thing that truly helps him compete in this game.
Kinaji 
RaZe 
Ichigo 
0mart 
Kira 
