Hello there :)
I’m relatively new to this tier but I’ve been playing a lot so I’m (hopefully) able to make a good VR nom now :D
Ahem swas told me to ahem
I’ll roughly start from the top and move down (and I’ll be using UMPL for my usage stats)
S+ (2) -> S+ (1)
S+ (1) -> S+ (2)
Bytes has already made this very clear and I totally agree. There’s honestly no reason not to use a Koraidon on every team except stall and UMPL stats show this, being consistently the most used mon. It’s by far the best scarfer in the tier, arguably the most threatening sweeper too and the multitude of setup sets to counter every counter makes me think this change is justified.
S (2) -> S (1)
S(3) -> S(2)
S (1) -> S (3)
I totally agree that defensive Ho-Oh is a fraud. You do practically nothing in front of an SD koraidon without tera, and scarf Koraidon 2HKOs you with outrage. Your only selling point is being immune to hazards and regen making you sort of a longer term solution to scarf Korai. I don’t think this justifies being higher than Arceus-Normal, the best offensive caly counter and great revenge killer and Arceus-Fairy, an actual SD Koraidon check, great setup mon and generally a pain to switch into.
It still think it has a lot of merit for offensive and specially defensive sets though so I still think it’s S tier.
Swas got to most of these lower ones before me lol ;-;
B+ -> B-
As swas said earlier, Deoxys-Speed is honestly the worst HO lead. I’ve also noticed it’s being used lot less now. In fact it was used 3 times the entire UMPL and lost all 3 games…
Deoxys-Speed gets you an absolute maximum of a single spike and rocks but likely not both and probably 0 value if your opponent has a Hatterene (which is definitely on the rise). I would argue glimmora is much superior, also guaranteeing a spike or rocks against most teams but can almost always get a tspike by preserving it after sash and throwing it out at a Koraidon trying to revenge kill later. Glimmora also has the added bonus of being able to spin off rimbombee’s webs and absorbing tspikes both of which are pretty catastrophic for HO.
Which brings me to…
B -> B+
I’ve already mentioned what most of what glimmora does above (it also cripples Hatterene with mortal spin unlike Deo-S). However, I think Glimmora is on the rise, actually seeing more usage than ALL the mons currently in the B+ tier in UMPL. I also personally think it’s a must on basically all HO whether it be plain hazard lead, webs or screens. It’s also just a pain to play around, even with a Hatterene. Hatterene can deny hazards but gets chipped and prevented from baton passing out due to mud shot. The only thing that could be passed to would be a scarfer, but with most teams’ scarfer being koraidon, it cant kill it either else a tspike gets set…
B -> B-
I’m not sure how popular Giratina-O used to be, but I definitely think it is not it now. It somehow manages to have the single worst typing against every S tier pokemon bar Arceus-Normal. It gets defog but is it really clicking it? When can it actually enter? It has no reliable recovery either, so other than Shadow Sneaking caly before tera (let’s be real though, is this really happening?) and Dragon tailing Arceus-Normal and -Ground (which would be nice to wisp, but you’re just getting taunted) I’m not sure what it’s good for and why you’d use it.
B- -> B
I personally think screens are very viable, and actually very strong at that. I’d say screens gives you a decent to good matchup into every playstyle except perhaps semi-stall and honestly feels kind of broken in general. Fat Draining Kiss caly behind screens alone is impossible to kill and honestly can take 3 or more kills before the screens turns are stalled out or it gets chipped enough for a scarfer to kill it.
B- -> C
I am the biggest Dondozo hater and I am convinced it does basically nothing well. Firstly, if your opponent has a miraidon, you’re just screwed as you have no healing. Honestly all it takes is a low kick from Koraidon, hard switch to Miraidon, u turn into Koraidon again etc a few times and the Dondozo has died achieving absolutely nothing (unless you’re both a madman running fissure AND you hit one). “Ok but what if you don’t have a Miraidon” well it’s still bad. Taunt ekiller beats it, Taunt Groundy beats it, Caly can enter on a rest and encore it. I genuinely don’t think I’ve lost with a Koraidon team to a Dondozo ever before. It’s that bad. It also hasn’t been used the entire UMPL when even EMPOLEON was.
That brings be to my next point…
Ok not actually but you gotta admit I totally got you :p
C+ -> B
Hatterene has been vouched for many times above to the point where I don’t think I have much to add lol. Usage has been going way up and it’s great hazard control for BOs. While Legendary Spam said it’s being teched around now, such as sludge eterns, and skill swap bees, that’s partially true but I still agree Hatterene deserves to be this high. Firstly, many etern are still not sludge bomb, and the ones that are can be scouted. Hatterene also primarily runs tera steel for this and mortal spin. If you’re also that worried about skill swap, run ability shield. If you’re worried about glimmora, run psyshock. If you just want to keep spikes and rocks off, just run a support Pain Split/Draining Kiss set. My point is Hatterene has a superb toolkit that makes it very viable and can be tailored to whatever your team precisely needs. It also has a lot more usage that something like Gliscor which is currently in B.
C+ -> D
Who invited this dude lol. I have genuinely never used or even seen this be used outside of a cheese smash pass Smeargle Dialga team geysers showed me.
C -> B-
Skeledirge in my opinion is a must have on practically all stall teams. It completely walls Ekiller and Zacian, and gives Koraidon a very tough time, and with help from Alomomola (or lefties if you’re willing to run bootless stall), can wall it over extended periods of time. It’s a million times better than Dondozo because it actually cripples things with Will o wisp and has reliable recover in Slack off. It’s also got Torch Song, which aside from being an insane move, prevents something like Taunt Arceus Normal from slowly Shadow Clawing it’s hp down.
C -> B-
Iron treads is a great counter to non-Overheat miraidon and the only real spinner in the tier. Sure it cant spin on a Ting Lu, but it has a ton of utility that makes up for it. Firstly, this helps a ton against stall. You deny Clodsire getting any hazards up, and force it out every time. You can set stealth rock, ice spinner a gliscor and knock everything else. I’ve crippled many Ho-Ohs using it by knocking when it switches into an eq. It’s also able to sit on an Eternatus, as nearly every etern doesn’t run a fire move, you deny tspikes, toxic and threaten it out with eq just like clodsire. A fully invested specially defensive treads (the only set in my opinion) also lives an unboosted astral barrage from full HP and OHKOs caly back with knock off (applicable if they try spinblock with caly). It also has a neat typing that allows it to switch into Zacian once and deal a lot of damage back (CC Zacian does not exist shh). What I’m trying to say is treads definitely has a niche and will likely always put in some work, so I definitely believe it deserves this rise.
C- -> UR
Swas has already mentioned this, and I agree. This thing gets no usage and has no niche.
UR -> C+
This has been mentioned before as well. It’s arguably the best stall breaker out there and can actually be a pain for BOs in case you get the fish wrong. Kyurem-White has insane fire power such that nothing can switch in, meaning if you manage to bring it in on say a Hatterene or Ting Lu, something is dying, punching holes for the rest of the team to take advantage of.
I’ve got a replay of Kyu-w doing it’s thing against stall from the winter ssnl:
https://replay.pokemonshowdown.com/smogtours-gen9anythinggoes-876776
UR -> C
I believe Corviknight could be a great asset for stall. Not only does it absorb knock off like Gliscor, it also can defog allowing for bootsless, or partly bootsless stall (more on this later). Corviknight takes ekiller and groundceus (also steel korai sets!) on easily and can help with Zacian too with an idbp set similar to skarmory, but with a much better ability. Corv also deals with ndm, one of stalls worst nightmares, really well, it resists every one of its attacks except sedge and can iron defence up to wall and threaten it. Pressure allows stalling out moves like Extreme Speed much more easily and can be used tactically in a pinch to say stall out Draco meteor pp. Corviknight can easily defog on Ting Lu, drain it’s spike pp and threaten it out with body press. Corv also walls the vast majority of eternatus and can defog on it too to prevent tspikes from going up. Corviknight matches Eternatus’s pressure and with a good plays (allowing 2 tspikes to go up before defogging every now and then) you can stall out all it’s pp.
I haven’t gotten too many replays of this myself but here’s one from ladder (you can see I’ve used less pp than eternatus):
https://replay.pokemonshowdown.com/gen9anythinggoes-2469472294-2te58knln16btcq1ul2uc02oi8reirspw
Here’s a great replay from UMPL that shows Corv off very well:
https://replay.pokemonshowdown.com/smogtours-gen9anythinggoes-875112
Right and about bootless stall. Why would you ever use something like that? It allows lefties mola and dirge, which now takes on korai much better. Lefties Blissey and Clodsire to take miraidon much better. Even mental herb mandibuzz so you can toxic the tera fairy dkiss taunt caly. It’s harder to play but it works much better at walling things long term. If you want a longer and better rant about bootsless stall, ask AGL :)
Anyway sorry for bad formatting and grammar I’m sure, and I hope I’ve justified my points enough and was in time for the vote ;-;
, 
, both to not worry about spikes and toxic spikes, and 
to be immune to sacred fire burn without worrying about spikes tearing up its hp, illustrated great in this team by geysers: https://pokepast.es/d25e2fad9b54fdf8. 
which no longer have to worry about spike chip and are therefore better switchins into 
switchin, leveraging its immunity to toxic, ability to bounce back tspikes and eternatus' complete inability to hit it, as most defensive sets lack a fire or poison move. Crucially, 
, shrugging off earthquake, and bouncing back spikes & whirlwind. As a side note, 
, Baton Pass passing calm mind or scouting an opponent's switchin, and Psychic being used by geysers for some ungodly reason, even though it does the exact same damage to 
: I think Lando-T should be moved to A- from A. It's not good at checking a Miraidon and Koraidon (IMO), even if niche teams like ones 
: I think groundy's in a very strange place in the meta right now. We've seen CM sets on niche BO teams built by people like 
: I think Rockceus is honestly never/rarely used despite IMO it being pretty decent as a defensive ceus. It's certainly a better check to 
pretty well with Will-O-Wisp while 
team featuring rockceus, though it may not be the finest team 
This mon is an absolute menace either with 
on fullroom (no example as of now because I'm not sure if 
+ 
: Added Arceus-Rock
Pecharunt UR -> C
UR-—>D/D-
C+ --> B
C+ --> B
C --> B-
C --> C+
UR --> C
C- --> C
C- --> C
B- --> C+
B- --> C+
C --> C-
C- --> D
C --> D
C- --> D
UR -> D
to C+
to C or C+
to UR
, once a Hatterene enjoyer but now a scarf ray enjoyer.