Celebiii's UU Metagame Predictions: Post-Kommo-o Ban
The Winners

: Roserade adores Kommo-o no longer being around to wall it and the general slower pace of the metagame, following HO losing a key piece. It still retains all of the great qualities it had before in tossing down Spikes and throwing out Sludge Bombs, but can do so much more freely in this new meta.

: Nihilego enjoys no longer having Kommo-o around as a switch-in to its Rock STAB as well as HO dying out. Nihilego works well on bulky offense and balance teams, greatly appreciating the slower pace of the meta. It is also a fantastic check to 2 very dangerous Pokemon that the community has had its eyes on recently in Thundurus-Therian and Galarian Moltres.

: Amoonguss might love the departure of Kommo-o more than anything on this list. It no longer needs to worry about Kommo-o ruining its Spore attempts with Overcoat, blocking its Sludge Bombs with Bulletproof, or just using it to set up one of its many sweeping sets in general. If Nihilego and Roserade increase in usage as I have predicted, it may even surpass Tangrowth again as the more common Regenerator Grass-type, as it can handle those two much better than Tangrowth.

: With the need for Fairies on every team dropping due to Kommo-o leaving (and their increased liability on a team given the Poison-types that are likely to rise in usage), Keldeo gets more room to breathe in this new meta. Its Speed tier remains as fantastic as ever, and with HO likely to decrease in usage, Keldeo will be more free to be slotted onto teams without opening gaping defensive holes.

: If Nihilego rises in usage as I predict, Krookodile will regain some of its former usage as a Rock resist. I feel that it is being underrated a bit in the current meta, as it does outspeed the extremely common lead Excadrill and still offers the same great role compression it always has. As well, with Poison-types likely to become more common, Krookodile is more likely to be paired with one of these, allowing it to be a bit safer against Mienshao and Conkeldurr. Finally, Krookodile itself appreciates not having to fear Kommo-o's many Fighting-type STAB attakcs.

: With Kommo-o's departure, Salamence faces less opportunity cost as a Dragon-type. As with Keldeo, it will also appreciate the likely drop in usage of Fairy-types. It will not appreciate Nihilego becoming more popular, but I wouldn't be surpised if Dragon Dance sets see a resurgence in popularity as win conditions on bulky offense and balance teams.

: Just like with Salamence, Hydreigon faces less opportunity cost as a Dragon-type now, and will appreciate the predicted decline in Fairy-type usage, even moreso than Salamence will, since Hydreigon's Dark STABs were actually resisted by the Fairies (unlike Salamence's Flying STAB). The overall speed of the metagame dropping is also friendly to Hydreigon, allowing it to be slotted onto more teams without worrying about speed control as much.

: Galarian Slowbro was often less effective against the hyper offense teams that dominated the tier recently, since it allowed several HO threats like Galarian Moltres, Dragon Dance Necrozma, and Swords Dance Aegislash to set up on it. With the metagame slowing down, Galarian Slowbro will likely increase in usage again as a bulky pivot, Calm Mind win condition, and (very unfortunately) Nasty Plot sweeper with Quick Draw + Quick Claw.

: I predict Zygarde-10% usage will only continue to rise with the increased viability of bulky offense and spikes teams in the coming metagame. It will also appreciate the predicted drop in Fairy-type usage, since these are some of its best checks.

: Similar to the above, a slower metagame and fewer Fairies makes for a friendlier environment for the OHKO crab. Kommo-o itself was also a huge roadblock for Crawdaunt, so it loves Clanger being banned.

: I expect Jirachi to rise up as one of the best checks to Nihilego in UU. If Salamence rises in usage as I expect it to, I predict that this was also greatly benefit Jirachi, as the two pair excellently together to cover each others' weaknesses.

: Lycanroc-Dusk appreciates a slower metagame that allows it to act as a late-game sweeper after its teammates have weakened the opposing team, compared with the previous HO-dominanted meta where it let in many dangerous setup sweepers. Many of the Fairies as well as Focus Sash Excadrill could also check it, and the decline I predict in their usage should allow Lycanroc-Dusk to roam UU a little more freely than before. Lycanroc-Dusk also appreciates defensive Kommo-o leaving the tier as defensive check to it.

: Mamoswine synergizes excellently with Spikes to pressure Pokemon immune to them (namely, Flying-types), so the expected increase in Spikes usage should be very friendly to it. It fits very naturally on the bulky offense styles I expect to rise in usage, and can check Thundurus-Therian offensively while providing the team with a Ground immunity and priority in Ice Shard.

: Rhyperior got some big wins with Kommo-o being banned. A very prominent Rock resist is no longer in the tier, Primarina and Excadrill usage is likely to drop, Amoonguss is likely to become more popular as a Regenerator Grass-type, and can help check the very dangerous Thundurus-Therian and Galarian Moltres. Expect it to become more common.

: With both Thundurus-Therian and Galarian Moltres on everyone's threatlist right now, (Choice Scarf) Gardevoir is looking like a very good safety net to have on a team against these threats. I expect rain to rise as the dominant weather in UU as well (not a dominant style, but moreso the most-used weather), and Gardevoir is an excellent weapon to have in that MU as well. Finally, if the other Dragons and Keldeo rise in usage as I expect, Gardevoir will have even more justification for a spot on teams.

: Cobalion functions much better in slower metagames where it can outspeed most Pokemon on a team while providing Stealth Rocks, a Dragon-type and Dark-type check, and pivot support with Volt Switch, and these are all characteristics that are likely to be needed in the coming metagame.

: I expect rain to rise up as the dominant weather in UU as people remember it can be quite good (especially with Thundurus-Therian around to abuse it) and with HO being less prominent (meaning rain faces less competition as an offensive playstyle). Politoed enables this style, and fortunately is also great against lead Excadrill, so I expect its usage to rise as well.

: Reuniclus appreciates not being overwhelmed by HO's raw power, which often did not give it a chance to set up or pivot around. With a slower metagame, I expect Calm Mind and Assault Vest sets to rise back up in prominence, especially since both sets act as great checks to Thundurus-Therian, Nihilego, Keldeo, and Galarian Slowbro. It also functions well in metagames with Spikes since Magic Guard allows it to bypass damage from them.

: Similar to Cobalion, Starmie functions best when it can outspeed most things on the opposing team, and a slower metagame provides that for it. Starmie is also less of a liability on a team when every member doesn't have to be depended on to check a hyper offense team threat. Starmie can offensively check many of the Pokemon that I expect to rise in usage above as well, so expect it to become much more common.

: Sun has seen an increase in usage lately and Venusaur in particular LOVES Kommo-o being gone, as it was a very common Pokemon that checked its boosting set with aplomb. I will also be interested to see if it gets used on teams outside of sun, as it does have a lot of great traits, particularly vs. stall with a sleep move, Toxic immunity, instant recovery, Knock Off, good bulk, and the ability to pressure the Unaware walls.

: Where sun goes, so does big Darm. Kommo-o was also a great check to it, so there is now one less thing around to stop Choice Scarf, Choice Band, and Heavy-Duty Boots sets from terrorizing teams again.
The Losers

: Azumarill being an HO staple means that the loss of a key HO Pokemon really hurts it. Azu was also able to offensively check Kommo-o, so its departure gives it one less target. The likely rise in usage of Poison-types is also very unkind to Azumarill.

: Specifically, I expect lead Focus Sash Excadrill to become less common due to HO losing Kommo-o. I do think the regular utility set will continue to be excellent (and will be great at spinning the Spikes I predict to become more common away), but Exca will have one less role, which should drop its usage a bit.

: Quite possibly the biggest loser of the Kommo-o ban. Primarina was an excellent check to basically every Kommo-o set, and will be less needed on teams following its ban. Like the other fairies, I predict the rise in Poison-type usage will also cause Primarina's usage to drop. I don't expect it to go to B rank or anything, as it can still be a very effective team player with any of its sets, and it will still be valuable in checking Dragons, Dark-types, and Keldeo, but I do expect to see less Prim soon.

: Sylveon also takes a massive hit with Kommo-o leaving the tier and the likely rise in Poison-types' usage. Unfortuately for it, it was already dropping in usage following the Latias ban, and another Dragon leaving the tier is doing it no favours.

: Potentially the least impacted of the Fairies by the Kommo-o ban, as it does function well alongside or against Spikes teams, and is always able to threaten Poison-types with its Psychic STAB. I may even be wrong here and we might see Hatt rise in usage - definitely a Pokemon to keep on the radar in the coming weeks.

: Galarian Moltres is one of the most iconic HO staples of this generation, and with the style likely to see less usage following the Kommo-o ban, I expect its usage to drop as well. Nihilego being much more viable is also not good for it. On the other hand, many people rate Galarian Moltres as one of the most dangerous Pokemon in UU right now, and Weakness Policy sets are still able to end games at the drop of a hat, so I don't expect it to become that much worse - just appear on fewer teams.

: The reasoning for Thundurus-Therian being in this category is the same as for Galarian Moltres - HO will likely become less prominent, and Nihilego will likely become more prominent. Similar to Galarian Moltres though, this may not mean it actually gets used less, just that it fits on fewer teamstyles, since it is public enemy #1 in the collective UU playerbase mind right now. In fact, pivot sets likely becoming more prominent may even cause it to become more popular than before.

: Stall teams were one of the most effective ways to deal with HO, and Chansey was on essentially every one of them. With the style likely to become less prominent, Chansey will likely see some drop in usage. It also really hates being pressured by Spikes and constant pivoting, which I see as becoming more common in the following metagame.

: More Poison-types in the meta and fewer physical boosting threats (most notably, Azumarill) is really bad for the Tangster. Kommo-o being gone also means that Thundurus-Therian is much freer to begin running Poison moves again, making Tangrowth a much less effective check. I would not be surprised if Amoonguss overtakes it in usage (again).

: Necrozma really wasn't used on many teams outside of HO, so with the style likely to decrease in usage, I expect we will see less of it as well. However, I could see other boosting sets such as Calm Mind becoming more popular, or even utility sets with Steath Rock and Knock Off.
Whew, that was a lot. Thanks a whole bunch if you read through all of that LOL. I'll be very interested to see how this new metagame shapes up and if my predictions end up being correct - many of them are predicated on Spikes and Poison-types rising in usage, and Fairy-types and hyper offense dropping in usage, so it's entirely possible I could be totally wrong. We'll just have to wait and see where this meta goes!