I think as far as VGC (slightly different meta than Doubles OU because of 4 battlers instead of 6 but *mostly* the same meta), these 6 are at the top of my personal tier list:
1. Galar Weezing
Neutralizing Gas is an absolutely meta defining ability, especially in doubles. It stops your traps, your weather, your intimidate/disguise/ice head, your offense/defensive multipliers, probably a significant piece of the opponent's strategy. It can also be a part of your own strategy.
Not enough? It can run Misty Terrain instead, a dope ability in it's own right. Poison/Fairy is likely an elite typing. It has very appreciable bulk (very strong in SwSh). And while its offense is pretty mediocre, it has a solid movepool for either a phys or spec set and is pretty evenly mediocre with either. It gets unique move Strange Stream, which isn't gamebreaking level good at all but is perhaps the best Fairy option available.
2. Gengar
Losing Levitate hurts pretty big. Losing a strong Mega evolution hurts, especially for a meta mainstay Pokemon that was already being pushed towards the outskirts of viability. But Gengar is still a Pokemon with a great typing (offensively, at least) and a stat line custom built for special sweeping. Sure enough, if Gengar wasn't a good enough sweeper to begin with, Nasty Plot was added to its movepool. Perhaps far more significantly, Mega Gengar almost feels reincarnated by Gengar's Gigantamax. Its special G-Max move adds the Shadow Tag effect of old, but it isn't an ability, so it can't simply be neutralized. Gengar brings the hurt and is likely one of the most reliable options to do so. The surprisingly deep pool of support options available only add to the reasons to see Gengar around.
3. Mimikyu
Mimikyu's Disguise has become a pretty reliable, and frequent, tool for doubles play. It makes Mimikyu perhaps the most reliable support option, as even doubling into it cannot KO it before it gets the chance to set up, unless one of the attacks is multi-hit, or also statuses Mimikyu. It was an extremely popular running mate to Snorlax, and although the reasons are different now than it was when that was last true, that combination will likely return strong. Galar Weezing presents a pretty crucial check to that "safe support" niche, but fortunately that is not the only reason Mimikyu is useful. Mimikyu also brings a healthy offensive movepool and decent offensive stats in it's own right. It has a great typing, and operates well within Trick Room strats as reliable set-up, independent of Trick Room because of its own high speed, and perhaps most effectively, as a Trick Room counterplay (using it again to turn it off, or forcing play around the potential to do so). Trick Room seems to be one of the most powerful presences in SwSh, and nobody has stronger Trick Room play than Mimikyu. Also, being a GREAT switch candidate to reset positioning shouldn't be ignored.
4. Tyranitar
Weather seems to figure to be pretty strong, but Tyranitar's value extends beyond just that of a weather setter. Tyranitar has long been very much in the heart of competitive battling because of it's very high base stats and extremely strong offensive options. This is only magnified by the limited pool of strong Rock type options in this game and the amount of really strong pokemon who are very weak to Rock type moves. Its typing is not good defensively, but its raw bulk largely makes up for this, so long as you can work around Fighting types. The ability that summons Sandstorm also helps this bulk, raising the SpD of all rock types by 50%. The difference to me, is that most weather setters are used for their ability to do so. And weather is potentially strong enough to justify this in SwSh; it certainly wouldn't be the first time the meta was that way. Tyranitar is useful, and strong, for the other aspects of its kit. AND THEN it gets its weather.
5. Alcremie
Ok... ok. I've been on the fence with this one. It's a support Pokemon, and it's hardly a safer bet than any other support, which is probably the primary qualifier for top tier usage. It is specially bulky, but not physically so. It is slow, and has no form of speed control, itself. However, the draw with Alcremie is that its capabilities are unparalleled. Nobody can make a potential sweeper as dangerous as Alcremie can. Decorate is an absolutely insane move. Alcremie also gets pretty much every other way imaginable to lower opponents attacking stats or to raise its allies defenses, as well as cure or prevent status. It does not get Heal Pulse/Life Dew, but its G-Max move makes up for that in droves. What's more, Alcremie can actually do some appreciable damage itself, it's not locked into a strictly support role like some. The Fairy single typing is pretty good too, though that's not huge.
6. Arcanine
Ok, hopefully this shouldn't require too much explanation. Arcanine isn't dominant, but it checks all the boxes as a solid option. Intimidate remains a strong ability, even with a few more checks this gen. The movepool remains a bit shallow, yet still very strong, with just enough options to make a fairly strong bruiser or a bulky support, and everything in between. Both are extremely viable. The single fire typing is perhaps more valuable than ever; the removal of Hidden Power makes Fire and Ice types offensively more in demand. The limited strong Rock options makes them better defensively, too. Seeing as how Fire directly beats Ice, I think Fire is a main competitor for the type that benefits the most from this gen. Incineroar will likely take Arcanine's spot as the bulky Fire Intimidate staple largely due to movepool, but rest assured that the niche IS a staple and that Arcanine will be a very familiar face occupying it in the meantime.
That's my opinion, anyways.
Honorable Mention- Hatterne. Seems like a very reliable Trick Room; Magic Bounce, Life Dew, strong SpA and ok bulk (kinda similar to Alcremie) make a very solid, well rounded threat that should see strong play. Perhaps not the best at any one niche but elite at a few, which is more than enough to be useful.
Also, I have to get this out there about one new Poke i see nothing about and have been looking into:
Greedent- I didn't at first, but now I love this guy. Absolutely stunning bulk, borderline elite there. Surprising attack- mediocre but not outright weak, which is more than good enough for something so bulky, especially a "first wild encounter" pokemon. Dumb slow, but slow enough to be quite a boon in Trick Room.
Here's the thing: Sitrus Berry + Cheek Pouch recovers 58% HP, even more than the super/pinch berries used to. This is a superior option to even gluttony/pinch, *even in gen 7*. Now that the pinch berries were nerfed to only heal 33%, this is a WAY better alternative.
Greedent gets Belly Drum. Here is a pokemon who's base stats honestly compare similarly or favorably to every other Drum user available-- and a MUCH better form of HP recovery than all of them.
Greedent, you beautiful, glorious, fat squirrel you.
Ok, final note without a long winded explanation: Mudsdale looks really solid in this meta. I don't even wanna try to guess exactly *how* good, I don't think its quite top tier. But m'boy is a stallion (pun sorta intended). Probably the strongest Mudsdale has ever been, even when it was getting some relatively frequent VGC play in 17' (I think that was the season. X&Y meta).
