Warning, long read
Although it still is pre-home and/or DLC right now and pokebilities has no chance of becoming an OM until then, I thought I'd make some theorycraft teams until the time finally arrives. Of course, I have a list of threats with the current Pokedex, but I'm less than half way through my doc detailing my thoughts on the potential threats, so releasing teams also helps me talk about the meta without having to write more in the document for 3 hours.
https://pokepast.es/0d0e08925ccab59a
Basic idea transferring into the new generation, hazard stack. Weather is definitely going to look much different compared to last gen, so I thought I'd start with something simpler.
First off, my favorite gen 9 pokemon, Clodsire. Basic bulky mon that stacks hazards, but it also has a ton of utility with its abilities. Abilities that heal from being hit by certain types of moves are more valuable than ever with the nerf to recovery moves, especially in the case of Clodsire, getting a major weakness removed. Obviously, it still is weak to ice, psychic, and ground, and it can still be hit by water type moves if the opposing pokemon has Mold Breaker (like a Basculin), but it is still a great defensive typing nonetheless. A great bulky pokemon to help out in rough situations while reliably absorbing Toxic and T Spike and setting its own hazards.
Amoongus felt like a good pokemon to pair with Clodsire thanks to it's ability to defend on the physical side of the spectrum. While both are weak to psychic, causing a very common weakness throughout the team, I do feel this was one of the better defensive cores I could make. Another way to try to get past stat boosting while spreading status and contact punishment, this time with both Rocky Helmet and Effect Spore. Doesn't even really need Synthesis often thanks to Regen. Foul Play is definitely situational and could pretty easily be replaced by Sludge Bomb, Toxic, or Stun Spore, but can still be helpful for strong and frail pokemon. I think that other than the two shared weaknesses, these two synergize pretty well and make a solid defensive core.
Ursaring is definitely one of the best returning pokemon for the pokebilities meta. While it definitely wishes it could run the speed for Adamant, the hit it takes from being forced to run Jolly to outspeed the base 100 and 105 tiers (hits an effective 107 base speed with max investment and Jolly nature after status), while significant, isn't as big as it may seem. Serving the role as either a cleaner, a wall breaker, or a sweeper from the strongest Facade in the game, Ursaring can plow through so much and seemed like a great fit on a team that focuses on hazards contact punishment (Effect Spore and Poison Point) because it makes it to where even less can switch into Ursaring's insane coverage
Breloom is a fan favorite returning pokemon that can do so many things, even if not all at once. While not as useful as prior generations due to the Toxic nerf, Poison Heal is still one of the best abilities imaginable. Top that off with Technician and you have one of the strongest priority users with insane stall breaking capability (Sub+Protect+Leech) and Breloom is easily top 10 without question. However, since I wanted to focus on breaking down teams by softening them up with passive damage, I felt Breloom would be best to be a revenge killer and wall breaker. Loaded Dice guarantees at least 4 hits on Bullet Seed. After Technician, 4 hit Bullet Seed is 150 BP, 5 hit Seed is 187.5 BP. You are sacrificing other items, but the higher consistency is a price I believe to be worth paying. Not only does it use an insanely strong Bullet seed, though, it also takes advantage of a boosted Mach Punch, which has the same power as a Scizor Bullet Punch. For anything that tries to switch in, I have Spore to punish if I haven't already slept a mon and Rock Tomb to lower speed and smack incoming flyers on the switchin.
Hariyama serves the role as a bulky attacker. Thanks to finally getting Drain Punch after 5 generations of the move existing, Hariyama has a form of recovery, even if not the greatest. This proves especially potent for Assault Vest sets because you are able to make yourself able to take more hits over time thanks to Drain Punch recovery. Status only helps Hariyama become more deadly, and fire and ice type moves both being resisted adds some nice defensive utility too
Finally, Azumarill. Losing Curse and Knock Off really sucked, but it's definitely not the end for Azumarill. While it only has Belly Drum, Assault Vest, and Choice Band, Azu poses a big threat with each set. Massive damage used to punch holes in opposing teams while also being able to be a late game cleaner, simultaneously having one of the best defensive profiles imaginable for an offensive pokemon. 4x fire resist, 4x ice resist, water resist, fighting resist, dark resist, dragon immunity, and grass immunity that boosts your attack because of Sap Sipper. Surprisingly defensively adept, Azumarill gets away with a ton from having both offensive and defensive capability, helping this team succeed both offensively and defensively
Edit: Here's a pokepaste for the same team, but replacing Amoongus with Slowbro. Helps with the psychic and ice weaknesses while spreading paralysis and pressuring the opponent with Future Sight
https://pokepast.es/351295eb16adcfb2