Rises:
UR ->
C+ Boasting Stealth Rock, Aurora Veil, Encore, and Thunder Wave, Aurorus makes for one of the best dedicated leads in the tier. Besides its utility options, Aurorus has incredibly high BP moves like Blizzard and Meteor Beam with Freeze Dry and Earth Power for perfect complementing coverage, making it a fearsome wallbreaker despite its poor defensive typing.
UR ->
C+ Regice has incredible natural bulk, which lets it make the fullest use of its fearsome BoltBeam coverage, with Focus Blast for Steel-types too. Regice can hide behind Subsitute using its great bulk to take advantage of special attackers like Vaporeon, Mantine, and Rotom-Mow, and can even boost its special attack with Charge Beam over Thunderbolt. Regice's SCL and NU Swiss debut have shown that its more than just "BoltBeam coverage on paper"
UR ->
C Ice-types are pretty good in the meta, huh. Jynx's Water immunity and solid special bulk let it thwart bulky Water-types, even sometimes using Heal Bell to cure Toxic. Nasty Plot with powerful Ice Beam, Psychic/Psyshock, and Focus Blast for coverage makes it extremely threatening to defensive cores should it get a free Nasty Plot. Jynx has laughable physical bulk though and its speed is only average in today's economy.
UR ->
C Ditto thwarts setup attempts from the opponent even without hitting the field, as offensive teams often cannot afford to setup as a risk of getting copied and reverse swept. Even besides setup sweepers, many defensive pieces like Mantine, Rotom-Mow, and Mudsdale sort of wall themselves, meaning Ditto can afford to use its opponent's utility moves against them as well.
A- ->
A Aerodactyl offers a ton of defensive utility despite being blisteringly fast, which cannot be said for almost all other defensive pieces. Beyond Stealth Rock, Taunt, Toxic, and Roost with a great typing, Aerodactyl's Dragon Dance set makes use of its amazing coverage to effortlessly clean up weakened teams.
A- ->
A Scrafty is a complete beast that outlasts most of its checks in the longrun and effortlessly shrugs off typically annoying hits like Knock Off and status moves with its Rest + Shed Skin combo. Choice Band and Dragon Dance sets can completely catch typical Bulk Up checks off guard and still put in immense work simply due to Scrafty's powerful Knock Off and Close Combat.
B+ ->
A- Dhelmise's defensive profile gives it a defined niche in the tier as hazard clearer that isn't weak to U-Turn or Volt Switch. Dhelmise's natural strength and coverage with Knock Off makes it quite difficult to switch into even as a defensive Pokemon.
B+ ->
A- Inteleon into a team without a Water-immunity just feels unfair. Its natural strength and speed makes it very overwhelming and its set diversity with Choice Specs, Choice Scarf, and Scope Lens make it very terrifying. Even into Water immune Pokemon, Inteleon can U-Turn on them into an abuser like Toxicroak or Heliolisk.
B- ->
B Spikes have always been powerful and Garbodor's ability to force Poison on common removers users like Mantine and Xatu, and just plain threaten out Rotom-Mow and Tsareena make its Spikes quite difficult to remove. Stomping Tantrum lets it hit Stakataka very hard, which has risen as the most common Steel-type by a longshot. Haze and Pain Split let Garbodor 1v1 Vileplume and Scrafty while getting Spikes up. Rocky Helmet + Aftermath mean that even postmortem Garbodor can put in work.
B- ->
B Despite our best efforts, Stunfisk-Galar has made itself a tier staple with compressing the Steel- and Ground-type with Stealth Rock and great bulk. This compression enables a ton of new options for teambuilding.
C+ ->
B- Arcanine's less crippling Stealth Rock weakness and better bulk than Talonflame has made it seen more on bulkier teams that appreciate its reliability. Arcanine serves as a sturdy check to Copperajah and Sceptile.
C+ ->
B- Rhydon compresses the roles of the 2 best Ground-types in Mudsdale's bulk and Stealth Rock, and Silvally-Ground's Swords Dance and overall offensive nature. Rhydon packs coverage for its common Grass-type checks like Rotom-Mow and Vileplume and can Swords Dance past many bulky Water-types.
B+ ->
B+ One of the most controversial Pokemon leading up to Indeedee-F's ban, Sceptile very easily dismantled teams with its insane combination of bulk and speed while under Terrain, which both lets it set up Swords Dance safely and be immune to priority moves. Sceptile's coverage let it bypass many checks, meaning only Weezing and Arcanine were reliable checks
Drops:
S ->
S- Stakataka dropping isn't so much a statement on its viability but moreso to demonstrate how good Rotom-Mow is comparatively as the solo S rank. Regardless, as Stakataka cements itself as the #1 Steel-type, it will be prepped for more often. Close Combat Escavalier, Low Kick Alolan-Exeggutor, Earth Power on Diancie, etc..
S- ->
A+ As Stakataka takes the place of the best Stealth Rock setter, Mudsdale also finds itself overwhelmed by the Toxic spam in the tier and also developments such as Dhelmise becoming better, Sceptile being more common, and both Low Kick and Focus Blast Toxicroak.
A+ ->
A With more diverse Water-types being seen, partially due to Blastoise ban but overall general meta shifts, Salazzle being able to exploit Vaporeon with Knock Off, Toxic, or Encore doesn't matter quite as much. More sturdy checks like Gastrodon and Mantine, while annoyed by these utility moves, can still reliably stave off Salazzle. Previously, Salazzle could make absurd progress regardless of which utility move it picked, but now it feels like the choice actually matters in each matchup.
A ->
A- Gastrodon's passivity in a tier with so many menacing Grass-types can be quite a detriment. Although Gastrodon has Ice Beam, it still has to pick between Scald and Earth Power, and a 4th move in Toxic, Clear Smog, or something like Yawn, as well as its item. Typically having multiple options is a good thing, but when you lose out on certain things because you dropped a specific move, it makes Gastrodon stretched too thinly
A ->
A- With Scrafty preforming a similar role and having a direct advantage against Snorlax, not only does this hurt Snorlax, but everything prepping to counter Scrafty indirectly counters Snorlax as well; Trick Rotom-C and Indeedee-F, Trapper or Growth Vileplume, Iron Defense Stakataka, etc.. Snorlax's great natural bulk is still amazing and puts in work, but it often struggles to Curse sweep as freely as it used to.
A ->
B+ Possibly overrated before, Tauros is a phenomenal wallbreaker with insane power and coverage AND amazing speed. Despite these qualities, Tauros is vulnerable to EVERYTHING; Rocky Helmet, all entry hazards, all status moves including Effect Spore and Flame Body, and almost no defensive utility in its typing and literally no resistances.
A- ->
B+ Physical sets having Shadow Sneak thwarted by Psychic Terrain is the biggest factor for Decidueye dropping. Having to resort to Choice Specs and Defog sets, both of which are relatively outclassed, its no wonder there's been less Decidueye seen. With Indeedee-F now banned, it can be expected Choice Band sets that can chip common Dark-types with U-Turn could be seen cropping up again in the future.
A- ->
B+ Heliolisk's constant battle to keep its coverage up to date with the metagame in a tier with Stakataka, Gastrodon, Snorlax, and many Grass-types is hopeless. In the right matchup it can beat slower teams down with super-effective moves, but its reliance on coverage to do lots of damage is a big hinderance.
B+ ->
B Diancie just keeps falling further and further down. It's lack of recovery and mediocre typing as a cleric makes it too unreliable for teams that need its clerical abilities. Offensive sets are quite potent at luring common Steel-types like Stakataka and Escavalier but fall short if properly scouted, and Rock Polish sets even after a boost can be too slow and struggle to set up in the first place.
B+ ->
B Tyrantrum is
extremely powerful and nothing else. Head Smash isn't even accurate and there's too many common Rock resists. Dragon Dance sets are too slow and frail, OHKO'd by Scarf Indeedee-F and Rotom-C.
B ->
B- Araquanid exploiting bulky Water-types is not exactly a unique niche anymore, and its poor speed and lack of recovery leaves it very vulnerable in long games, which Araquanid is specifically supposed to be good in.
B ->
B- Drampa's Choice Specs sets are simply outclassed by other Specs breakers, but its Calm Mind sets are neutered by Toxic and is always lacking coverage for
something, needing a STAB move, Calm Mind and Roost, and one of Fire Blast, Surf, or Focus Blast, which is always walled by something.
B ->
B- Exploud was often outclassed by Indeedee-F due to them having similar power levels but Exploud is slower. Exploud's coverage is better and if it gets the read on the Steel-type it can often steamroll games but there are breakers that don't have to predict at all
B- ->
C+ Grimmsnarl simply falls short as a wallbreaker because it lacks in offense, speed, and bulk. It's Prankster sets are fancy but Bulk Up RestTalk has to pick what it loses to and with Light Clay banned, screens aren't worth running an otherwise useless Pokemon.
C+ ->
C Much like Garbodor, Froslass is one of a few good Spikes users. Unlike Garbodor, Froslass lacks the longevity needed to keep Spikes up in the longer games that Spikes would be more useful in. It's quite easy to just take out Froslass then remove the Spikes later.
C+ ->
C Magneton's trapping set is quite effective, but there's better ways to take out or weaken Steel-types while using a Pokemon that offers more beyond just that.