i think there's definitely a valid argument to deny zss a top 10 position, and to call it an 'outlandish' position ignores several practical issues with the character that come to light at the top level of play. zss is a good enough character to place consistently very well with at big tournaments in the right hands. her mobility, disadvantage state, and lethal punish capabilities are all top tier qualities that give her the options to perform well in most mus. that said, zss has numerous flaws that lead to some debilitating matchups, a factor that all of the top zss players and some others understand well.
1) lack of safe rising aerials and safe grounded pokes. this essentially means that zss's safe attacking options are limited to spaced falling aerials, which are safe on normal shield but unsafe on powershield. having to do the falling aerial makes timing a powershield much easier, particularly if you crouch to lower your hurtbox and also make timing the powershield easier. relying on falling aerials also makes zss vulnerable to quick air-airs and certain anti-air options, particularly certain pp up tilts. she has just enough options alongside her mobility to have a serviceable neutral and effective offense, but there's just blatant holes that become really obvious in certain matchups and against players that know how to exploit them.
2) bad grab. this is really basic info, but zss's grab has pretty severe issues. it's not even that rewarding unless you have rage or platforms to convert the grab into a ko. this makes shielding against zss very strong. it is nice that zss can confirm into grabs in a few different ways between nair, zair, and paralyzer, but lack of an oos grab and the general unsafeness of her grab are major flaws. if you watch choco vs ken, you see that almost all of choco's grabs are straight callouts in neutral. marss and nairo do these as well, sometimes just throwing grabs out when the risk/reward is in their favor (or even not). it's rewarding for them when they land the grabs, but there's also many examples (even in sets they win) where they get punished heavily or just cannot land their grabs.
3) mediocre kill options past ladder percents. at high percents, zss often can't do much to kill other than fish for bair. she doesn't really have a grab to ko at high percents (if her dthrow is di'd properly and particularly with rage) or many real setups into ko options except out of dsmash. she can also up b oos if you touch her shield unsafely, though it's a pretty unreliable option because falling out of up b is so common, especially with certain characters. watching umebura tat, nairo was making comments in the chat about how zss struggles in last hit situations, and you could really see it in the grand finals of choco vs ken. what ken does against zss players is he utilizes his sonic playstyle and they just can't hit him, particularly at ko percents. it's hard for choco to fish for back airs when ken catches all kinds of jumps with a rising back air of his own, so getting kills at high percents is extremely hard. now apply this to other characters that punish those jumps easier and harder than sonic does - particularly bayo and cloud. this issue becomes very apparent against these characters, particularly because both of them tend to fall out of up b, which is part of what makes these matchups so difficult for zss.
4) her hitboxes don't hit low well. this makes short characters, even if not quite losing mus, a huge pain for her to fight, as well as characters with low crouches.
as for matchups, i tend to agree with
Galaxeon
in that her top 4 mus, particularly against the top 2, hold her back a good deal. with 2-3 -2 mus, you could still make an argument to put zss in top 10, but having 2 of those matchups be against the top 2 characters in the game is a huge flaw when those are by far the most relevant mus. explanations on zss vs top 4 mus:
- bayo beats zss in just about every facet of the game. her crouch, dtilt, nair, wtw, and wt in particular make neutral a huge pain for zss. bayo beats zss in terms of damage output. her normally incredible disadvantage state falls apart in the face of bayo's brutal edgeguards and ability to follow flip kick easily with abk. she also has a tendency to fall out of up b in a way that does not kill her and puts zss in a disadvantageous position, neutering zss's punish game. it is clear why this is considered zss's worst mu, and we see this in salem's dominant record against nairo as well as some of nairo's other more recent losses to bayo. choco has also struggled in this mu against 9b. marss has lost to mistake and zack in this mu, though he has beaten zack before.
- although there isn't quite as much consensus on this mu, i would make the argument that cloud is nearly as difficult as bayo for zss. cloud's range and busted air-air/anti-air options are very difficult for zss to deal with. combine this with cloud falling out of up bs in the same unfortunate manner that bayo does and you're not looking at a good mu. the main reason this mu is slightly easier than bayo is that killing cloud, particularly with successful reads in advantage state, is less of a chore. we've seen nairo succeed in this mu against komo and other lesser clouds, but both tweek and leo have looked very difficult for a long time at this point. marss has also struggled in this mu. choco has an alright record against japanese clouds, but he's still lost to a few of them, including rain, mangalitza, and selcia. he was pushed to the limit by kameme's secondary cloud this past weekend at umebura tat as well.
- sheik is probably zss's third worst mu. we've actually seen nairo be very successful in this mu in his victories over mr.r and void in particular, but nairo and zss players in general still lament this mu. the main factor zss has to succeed in this mu is her rage ladder, which confirms really well on sheik, but aside from that, this mu is just difficult. sheik's oppressive safety/slippery nature in neutral, low crouch, high damaging punish game, and ledge trapping make this mu an all-around pain for zss. it's probably just a -1 mu at this point, but it's borderline -2.
- diddy is a mu that has actually been getting better over time, but zss still loses it. fair and banana are too effective as walling options, and diddy's movement combined with his small hurtbox makes hitting him difficult for a character who has issues with short characters in general. that said, diddy's lackluster disadvantage state and particularly his poor aerial drift make zss's punish game very effective against diddy. moreover, diddy punishes zss's jumps and her options in general worse than other characters. this makes the risk/reward of throwing out grabs, for instance, a lot better than other mus, allowing her to overcome the advantages diddy has to prevent these grabs.
compare zss's mus against the top 4 to other non-top 4 characters. rosa struggles with cloud a lot and has some issues with bayo as well, but she does much better against bayo and beats both sheik and diddy. sonic loses 3 top 4 mus (bayo, cloud, and sheik), but only one is potentially -2, that mu being bayo. pika is generally seen to go even with all of these characters, with some of them even being a potential slight advantage for him. corrin goes even with bayo and probably loses -1 to the other 3. mk goes even with cloud and loses -1 to the other 3. although mario struggles with bayo and cloud as well, he does better in both of those mus and goes even with sheik while arguably beating diddy. ryu goes even with sheik that loses the other 3 only -1, with the possible exception of diddy. marth goes even with bayo and probably loses only -1 to the other 3. see how many characters perform blatantly better against the top 4? not all of these characters are necessarily better than zss, but i would argue many of them are, especially rosa, sonic, pika, corrin, and mario.
the top 4 doesn't even include all of zss's losing mus. pika is probably ~as difficult as sheik, the best example of a character that abusing zss's difficulties with characters that have small hurtboxes, good air-air/anti-air options, and disadvantage states that she cannot abuse. next, factor in zss's lack of dominance against the cast in general. nairo lists 11 even mus, and some of the +1 mus that he lists, like olimar, mk, and g&w, are generous and more than likely even mus. aside from heavies, zss does not have a single mu better than +1 against a non-low tier, and she does not beat every low tier better than +1. she does not beat any top tier. with a worse spread against the top 4 than several characters, no winning top tier mus, and a relatively unimpressive spread against the cast as a whole, zss struggles to qualify for a top 10 spot.
Shaya - I’d imagine you know this, but I haven’t read it as confirmed, but her infamous rage combo isn’t actually a sure thing either, correct?
. 
gets underrated because his lack of explosive options. It's easy to freak out when you get smash4ed by Ding dong or limit cs but look at it from the other side. Neutral strong characters like Sonic and Diddy are just as scary. You lose 4 out of 5 times to largely safe options then get pressured across the stage and probably ledge trapped. That's as potent as anything combo heavy characters can do.
