Hello everyone! It has been a darn while since I have done a metagame post so I will put some of my thoughts of the metagame here since a bunch has changed in regards to my opinions.
Firstly my new top 10 with some extra thoughts!
1.
By far and away the best Pokemon in the metagame. No singular mon does as much Rillaboom does, it has offensive pressure with Grassy Glide, defensive utility with Fake Out, U-turn, Taunt, and Grassy Surge, has a unique typing that makes it stand out amongst the roster. Rillaboom also helps Pokémon like Palafin and Kartana. For Pokémon like Palafin and Urshifu-RS, Rillaboom can create dead turns for them to click moves (or switch out and gain Hero forme in Palafin's case) and remove opposing terrain like Psychic Terrain which blocks Aqua Jet and Jet Punch, or even Electric Terrain to remove Iron Bundle's Quark Drive to Scarf Pokémon can outspeed it. Kartana is an off case that straight up benefits from the Grassy Terrain, making it launch Leaf Blades the power of nuclear warheads. Aside from that Rillaboom is also a really good Chien-Pao partner, and this makes them form the deadly Rillaboom Chien-Pao Kartana core, which makes Kartana effortlessly 2 shot resists with the click of a button. Rillaboom is most commonly used as an Assault Vest pivot, but Sitrus Berry with Taunt or Choice Band with Chien-Pao are very much so usable.
2.
Well some nuclear warheads don't need a damage ruin and terrain support yeah? That nuclear warhead is Flutter Mane. This beast of a Pokémon does not even worry about resists like Kartana does, as it has practically none. Flutter Mane can also be surprisingly bulky, being able to live a Mega Metagross Bullet Punch or even a Tera Dark Black Glasses Kingambit Sucker Punch. A lot of the time Flutter Mane forces Tera to beat it due to its coverage and power and speed, and it is pretty splashable of a Pokemon due to its offensive prowess and close to no terrible weaknesses. Although it does struggle here and there versus SemiRoom teams and Prankster Tailwind, its other traits outweigh these weaknesses greatly. Choice Specs, Booster Energy, Focus Sash, and even Pixie Plate sets are excellent. Non-Specs sets can even be used as a secondary Trick Room setter in SemiRoom teams.
3.
Still the king of megas eh? Salamence just gets so much done for a singular slot its insane. Great damage output, great typing, Tailwind and Breaking Swipes support, ability to setup and sweep. Flying resists are also very sparse to the point of Salamence being able to trade in almost any game if it didn't take an Ice Spinner in the face while trying to get into the field. With the uprise of Jirachi and Chien-Pao, Mega Salamence has solidified its place as the king of megas due to its general synergy with the tier and how it abuses the metagame. With Jirachi it can get up a lot of Dragon Dances or setup Tailwind safely, and its Tailwind set synergizes with Chien-Pao teams greatly while having deadly Double-Edges due to Sword of Ruin. Both Tailwind and Dragon Dance sets are extremely splashable. Tailwind can run bulky, all out physical, or even mixed, and Dragon Dance prefers going bulky to get even more opportunities to setup.
4.
Water/Fire with Water Absorb is just so god damn excellent of a STAB combo and defensive combo, bolstered by Volcanion's great defenses and the power of Steam Eruption, Volcanion is by every meaning of the word incredible. With few and sparse weaknesses it has great staying power and it makes those turns count as it has a really strong STAB water move and a spread STAB fire move to click on the opponent. It also has coverage for itself and Tapu Fini. Resisting Fairy while not being weak to Ghost is also huge in regards to its Flutter Mane matchup as the better steels in the format are either weak to Ghost (Jirachi and Mega Metagross) or are neutral to Fairy (Kingambit) or might as well not resist wink wink Kartana. Assault Vest sets excell at checking Flutter Mane, Chi-Yu, etc, meanwhile Safety Goggles helps it against Amoonguss and Leftovers with Substitute under Grassy Terrain is very hard to take down.
5.
I think number 5 is a toss up between Tapu Fini and Jirachi, but I believe Jirachi has more potential to being broken than Fini. Jirachi is a really annoying utility demon. It cannot get much done by itself, but it enables so much by the power of Follow Me, Encore, Trick Room, and Iron Head flinches. The bulk of it is also absurd, one of the only downsides of it is the Psychic-type tacked onto its perfect Steel-type. But of course, Tera completely fixes this issue, as Tera Water and Tera Fairy Jirachi make Jirachi even more absurb and its partner even harder to take down. The other downside of Jirachi is the lack of variance in sets, as it has 1 set with 3 last move options compared to most of the other top 10 Pokémon which have at least two sets (there being another exception which I suppose you might be able to guess or just read down). But this does not hold back Jirachi as much as you would think it does, as Follow Me is such an unique role to fulfill that Jirachi really does not need the variance to be more than excellent.
6.
Tapu Fini my beloved, as you can guess by my avatar is my favourite Pokemon of all time. Both design-wise and usability in Doubles. Tapu Fini is really fun for me as it can go Support, Setup, or even full on Offensive. Tapu Fini has an expansive movepool especially in the supportive department, it has Nature's Madness, Taunt, Heal Pulse, and Icy Wind. These moves make Tapu Fini great at supporting bulky offensive teammates or teammates with setup moves. On the topic of setup moves, Tapu Fini is the best Calm Mind user in the tier. With a great typing, a lot of bulk, natural Spore immunity, and some Intimidate and redirection help, Tapu Fini can easily sweep a team. Its sweeping capabilities are helped a lot by Tera as one of the main things holding Tapu Fini back is its weakness to Rillaboom. Offensive sets with Choice Scarf and Choice Specs are less common and not as good as the other sets, but they are still very much so usable since Fairy and Water are great STABs and Tapu Fini has the bulk to fire off multiple Choice Specs Muddy Waters.
7.
If Jirachi is the utility demon, Incineroar is the utility satan. Incineroar really has every bit of support in its arsenal. Intimidate, Fake Out, Knock Off, Parting Shot, even Taunt in edge cases. But Miss Glimmer! If Incineroar has so much utility and was so good in previous gens, why is it so much lower??? I hear some of you asking. Well my innocent and young child, it is what I like to call "the Flutter Effect" or "Manes of Doom" if you wanna be metal. Incineroar's typing is good it just is not that great into the meta all things considered. Being a Fire-type that does not resist Fairy also severely damages its Flutter Mane matchup, as it needs to run Assault Vest and give up on Parting Shot and hazard immunity to be a check to Flutter Mane. But this is not to say Incineroar is not fantastic, there's a reason it remains in the top 8. It is still the best Intimidate Pokemon by a good margin, Fake Out and pivotting and Knock Off are great utility. Incineroar's sets are pretty one dimensional with really only a few move changes here and there due to teams. But it has quite a few items it can run. On more offensive teams most Incineroar still opt for Safety Goggles or Sitrus Berry. There are off cases where some like to run a Shuca Berry to better rid of Zygarde and Landorus-T. And on more defensively geared teams Incineroar likes to use Heavy-Duty-Boots to avoid chip while pivotting around spamming Parting Shot, or the aforementioned Assault Vest due to Flutter Mane.
8.
Remember me mentioning Kartana and Flutter Mane as nuclear warheads? Considering they are, Mega Metagross is more like a black hole going nom nom on all the neutrals. Steel Roller does absurd damage with the Tough Claws boost but its honestly kinda awkward. You generally need to run both Rillaboom and Tapu Fini for this to function which may be awkward in and on itself, but Steel Roller also makes it lose out on either consistent Steel-type moves or Bullet Punch. Since we talked about the negatives right away here are the many positives. Steel Roller does massive damage to even the bulkiest of resists, 3hkoing Incineroar with a resisted move from a physical attacker with no extra boosts is a thing that only another mon has done, and Urshifu-SS is currently banned. Movesets which don't carry Steel Roller are still very good as Mega Metagross has coverage for practically everything. Stomping Tantrum for Kingambit, Incineroar, Jirachi, Iron Hands, Stakataka, Chi-Yu, and Volcanion, Ice Punch for Mega Salamence, Rillaboom, and Landorus-T, and Thunder Punch for Urshifu-RS, Tapu Fini, Mega Charizard Y, Basculegion, Palafin, and Volcanion.
9.
Yes dear scroller, this is the other one set wonder I was talking about, you can return to the Jirachi post now. Jokes aside, Chien-Pao is a great Pokemon but unlike in singles, Chien-Pao here is mostly used to boost teammates attacks with its Sword of Ruin to boost the strength of already extremely strong Pokémon like Kartana and Urshifu-RS. This is not so overshadow its offensive capabilities, Ice Spinner is a great move that also removes terrain and Chien-Pao's Sucker Punch is a great and strong cleaning tool. Chien-Pao can get paired with most physical attackers aside from Iron Hands who likes to keep its bulk to itself, so the synergy potential of Chien-Pao is a lot and it forms a lot of offense teams around itself because of this.
10.
Had a really rough time deciding between Unseen Fists, Prankster Tailwind, and Spore + Rage Powder for the number 10 spot, but Urshifu-RS won me over. The only real issue with Urshifu is that it doesn't do super great into some of the other super meta defining Pokémon. Rillaboom, Flutter Mane, Tapu Fini, Mega Salamence, Amoonguss, even Tornadus all kinda destroy it. But aside from that, it is literally the perfect physical attacker. It ignores most traditional forms of fending off physical attackers with big buttons, being Intimidate and Protect. Surging Strikes also goes through Focus Sash which is another way of point blank cancelling other strong Pokémon like Mega Salamence. These traits paired with a good STAB combo and the ability to blow past checks with Tera Water or Tera Grass really sells the top 10 spot to Urshifu. It also has decent set variety, although all of its sets primarily click the same buttons they play a whole lot differently. Bulky sets with Assault Vest or Mystic Water can throw out a ton of damage while having a bunch of defensive utility and staying power, Choice Scarf is solid in Rain or with Chien-Pao, Choice Band and Life Orb do tons of damage to pretty much everything.
Aside from the top 10 I also want to talk about some more Pokémon that I found solid/underwhelming.
Setup Zygarde is really really busted with Tera and Jirachi. Tera Water, Steel, or Fairy sets with Substitute have a really easy time setting up and staying behind the Substitute, Tera Normal becomes immune to Spectral Thief and Shadow Sneak and gains STAB for Extreme Speed. Choice Band Zygarde is still decently notable and is great at dealing chunks of damage at a whim, and becomes even more destructive with Tera and Sword of Ruin.
It sits. It clicks Spikes. Life is good. I really do believe Spikes have incredible value in this format and Ting-Lu is the primary setter of them. With a good typing, incredible bulk, and busted ability, it can easily stack up Spikes and open the ways of tons of Balances. I specifically like it paired with Tapu Fini and Jirachi as Jirachi allows Ting-Lu to set up Spikes more comfortably and since against Tapu Fini + Jirachi you have to switch around a lot to prevent getting swept, both Tapu Fini and Spikes get a ton of value.
Zapdos is surprisingly solid from the time I have used it, it can still pull off the bulky Misty/Psychic Seed Tailwind shenanigans, it also uniquely resists Mega Salamence's Double Edge and Mega Metagross' Steel Ground combo. With a practical AV paired with recovery and Tailwind and Tera, Zapdos can stay on the field and get a lot of value. Obviously it is not included in the list as this tiermaker has mons from current and past Viability Rankings.
I love Stakataka. You may say it takes a lot of commitment which it does, but it is absolutely worth it. A Tera Water or Tera Flying Stakataka is so ridiculously hard to take down while doing great damage and boosting its damage output even more. The only downside of Stakataka is the Tera and Trick Room investment which honestly, I am more than willing to give it for how good Tera Stakataka is.
Basically a way less commital version of Stakataka, Diancie does not need Trick Room up, already has decent typing, but Tera Diancie is almost as ridiculous as Tera Stakataka. Diamond Storm + Body Press is only held back by Marshadow who I am not super high on and Urshifu-RS who is annihilated whenever Diancie decides to Tera. It is also a more self-sufficient Trick Room setter than Stakataka so I overall like it more.
Yes I have been praising Trick Room mons but, Ursaluna is not as self sufficient or good outside of Trick Room, while Stakataka and Diancie can function really good in SemiRoom and set Trick Room for themselves. But Ursaluna is still one of the best abusers of Trick Room so I am not gonna put it that low. Im just not super high on Pokémon who only work under Trick Room and have a hard time outside of it while not being able to set it, and Ursaluna is one of these Pokémon.
The other one of these aforementioned Pokémon is Mega Camerupt which honestly has a good case for being UR. It just has the same weaknesses as Ursaluna and does a way worse job at it due to lack of burst and not being able to Tera. Mega Camerupt is also more strictly used in FullRoom which is honestly quite bad in the current state of the meta. If I need a mega for my Trick Room team I am either picking up one of the top 3 or Mega Gardevoir.