Hi, I ran two teams for my climb during the opening competitive hours of Season 6, or the early morning hours for where I live. It wasn't very fun!
https://pokepast.es/7f8cdd05cfa669f3
This team was thrown around by a couple others in the Discord server, so I decided to try testing it out. Out of the 16 matches I used it for the climb, I went 11-3-1-1.
Standard Garchomp set that does what it usually does well for the most part. I originally had Poison Jab for the last attack to deal with Xerneas better, but I opted for Dragon Claw to have a better handle opposing Garchomp and Rayquaza leads; Dragon Rush + Poison Jab barely missed out on the KO against the latter during the start of one match.
Kyogre is a very strong sniper that can easily end ongoing one-on-ones as a third party, but its large frame and status as a Restricted Pokemon enforce it to be positioned well. I went with Expert Belt and BoltBeam coverage to handle Water-types like opposing Kyogre and Golisopod and the Dragon-types, but I think running dual STAB moves with Mystic Water may be viable as well.
I also tested Primal Kyogre as my lead for the first few matches of my run, mainly because I hear negative opinions about it over on the Discord server. I think it's okay, but Primal Kyogre's even larger size and the awkwardness of Primal Reversion's animation eating up valuable seconds, even on respawn, makes Blue Orb just an option.
This is the same Melmetal set that was put out for Season 5's metagame, but with BoltBeam coverage. I think it still performs well in big all-out fights, and its niche is expanded given Xerneas's presence, but I think the increase in overall bulk among the popular threats, in addition to the notion that most competitive players do not attempt to make the first move, exposes Melmetal's sluggish movement speed more than it did last season.
https://pokepast.es/ccf9f46c3fca0f4e
I wanted to try out Rayquaza with dual screens support due to the allure of two potential Mega Evolution options. Out of 11 matches I used this team to climb, I went 9-0-1-2.
Dual screens Ampharos does its job well enough, but I think the addition of Groudon means there were a couple times I have to sacrifice it because I have no more switches to burn and every opponent sent out a Ground-type. Other Pokemon like Golisopod and Leaf Blade Sirfetch'd also make it difficult for me to take advantage of dual screens.
Both Rayquaza and its Mega Evolution are very powerful Pokemon that can easily track and smash opposing Pokemon with its dual STAB moves, and the freedom to just go at it without Mega Evolving is also nice. That said, Dragon Ascent is a bit awkward to use; the startup animation where Rayquaza roars doesn't have any invulnerability to keep it safe, and even when it comes down to strike, it can still get clipped by a beam and get knocked out before the attack actually lands. This might result in treating Dragon Ascent similarly to Marshadow's Spectral Thief where you may want to hold off on ordering it until a fight breaks out, which might be crucial given Rayquaza's presence.
On a side note, I did try Life Orb due to the sheer damage boost, but I think the overall power level of the metagame as well as Dragon Ascent's defense drops makes it too risky of an item choice for me, even with dual screens support.
Mega Swampert feels like a pretty strong Pokemon at the moment because it can handle Primal Groudon, Melmetal, Garchomp, and Rayquaza pretty well, but I also tried base Swampert out to decent or good effect. However, I think the presence of previous established threats like Solar Beam+ Armarouge and Volcanion and Leaf Blade Sirfetch'd as well as new adaptations like using Virizion might knock its presence down a bit; it felt a bit difficult to make any headway in later matches given these observations.
The overall climb ended on a 20-3-2-3 finish, which seemed pretty good given the competitive environment. However, I went ahead and tested the teams out some more to get a more clarified opinion on the overall metagame state, and it wound up turning into a more sour 24-8-6-3, out of a total of 41 matches. (team use was evenly divided)
Some observations from my matches:
There were a lot of players running Fire-types with Solar Beam+, which made trying to play around them annoying. Volcanion has a better typing against the newly introduced threats, but Armarouge's sheer power with Meteor Beam has enabled some opponents to lead games away, so it's not a threat to be discounted imo. There were a couple Glaceon that made piloting the Rayquaza team very difficult given Freeze-Dry and Glaceon's decent physical bulk, and there were a good chunk of Virizion players in the post-climb matches that gave me trouble with the Kyogre team.
(Meteor Beam) 
There were a few players that opted for Meteor Beam Rayquaza to good results. Some Rayquaza seemed to be mixed attackers with Dragon Ascent, but I don't remember if they have Meteor Beam. There were a couple Aurorus brought to battle; it might have some use given its type advantage against some of the new Restriced Pokemon.
A couple players opted for Hoopa, and at least one of them ran away with the game. I'm not sure if it'll hold up against the Restricted Pokemon, but its superb Special Attack and small stature may grant it more steals during ongoing fights than its Unbound forme.
As for my experience with my climb, while I do think the overall power level and variety of threats to account for may contribute to this, I really did not like playing due to my very sloppy mistakes and the constant stream of competitive matches, which made me way more stressed out than I should be. The nature of competitive matches starting with a "Who goes first and gets punished?" type of deal followed by the cascade effect of "KO after KO after KO after..." or "player steals KOs with little contention then wins", combined with the absurd strength and big red targets of most Restricted Pokemon, is dissuading me from devoting more of my free time to this season, and I already didn't spend much time for the past two seasons either due to other reasons.
https://pokepast.es/7f8cdd05cfa669f3
This team was thrown around by a couple others in the Discord server, so I decided to try testing it out. Out of the 16 matches I used it for the climb, I went 11-3-1-1.
Standard Garchomp set that does what it usually does well for the most part. I originally had Poison Jab for the last attack to deal with Xerneas better, but I opted for Dragon Claw to have a better handle opposing Garchomp and Rayquaza leads; Dragon Rush + Poison Jab barely missed out on the KO against the latter during the start of one match.
Kyogre is a very strong sniper that can easily end ongoing one-on-ones as a third party, but its large frame and status as a Restricted Pokemon enforce it to be positioned well. I went with Expert Belt and BoltBeam coverage to handle Water-types like opposing Kyogre and Golisopod and the Dragon-types, but I think running dual STAB moves with Mystic Water may be viable as well.
I also tested Primal Kyogre as my lead for the first few matches of my run, mainly because I hear negative opinions about it over on the Discord server. I think it's okay, but Primal Kyogre's even larger size and the awkwardness of Primal Reversion's animation eating up valuable seconds, even on respawn, makes Blue Orb just an option.
This is the same Melmetal set that was put out for Season 5's metagame, but with BoltBeam coverage. I think it still performs well in big all-out fights, and its niche is expanded given Xerneas's presence, but I think the increase in overall bulk among the popular threats, in addition to the notion that most competitive players do not attempt to make the first move, exposes Melmetal's sluggish movement speed more than it did last season.
https://pokepast.es/ccf9f46c3fca0f4e
I wanted to try out Rayquaza with dual screens support due to the allure of two potential Mega Evolution options. Out of 11 matches I used this team to climb, I went 9-0-1-2.
Dual screens Ampharos does its job well enough, but I think the addition of Groudon means there were a couple times I have to sacrifice it because I have no more switches to burn and every opponent sent out a Ground-type. Other Pokemon like Golisopod and Leaf Blade Sirfetch'd also make it difficult for me to take advantage of dual screens.
Both Rayquaza and its Mega Evolution are very powerful Pokemon that can easily track and smash opposing Pokemon with its dual STAB moves, and the freedom to just go at it without Mega Evolving is also nice. That said, Dragon Ascent is a bit awkward to use; the startup animation where Rayquaza roars doesn't have any invulnerability to keep it safe, and even when it comes down to strike, it can still get clipped by a beam and get knocked out before the attack actually lands. This might result in treating Dragon Ascent similarly to Marshadow's Spectral Thief where you may want to hold off on ordering it until a fight breaks out, which might be crucial given Rayquaza's presence.
On a side note, I did try Life Orb due to the sheer damage boost, but I think the overall power level of the metagame as well as Dragon Ascent's defense drops makes it too risky of an item choice for me, even with dual screens support.
Mega Swampert feels like a pretty strong Pokemon at the moment because it can handle Primal Groudon, Melmetal, Garchomp, and Rayquaza pretty well, but I also tried base Swampert out to decent or good effect. However, I think the presence of previous established threats like Solar Beam+ Armarouge and Volcanion and Leaf Blade Sirfetch'd as well as new adaptations like using Virizion might knock its presence down a bit; it felt a bit difficult to make any headway in later matches given these observations.
The overall climb ended on a 20-3-2-3 finish, which seemed pretty good given the competitive environment. However, I went ahead and tested the teams out some more to get a more clarified opinion on the overall metagame state, and it wound up turning into a more sour 24-8-6-3, out of a total of 41 matches. (team use was evenly divided)
Some observations from my matches:
There were a lot of players running Fire-types with Solar Beam+, which made trying to play around them annoying. Volcanion has a better typing against the newly introduced threats, but Armarouge's sheer power with Meteor Beam has enabled some opponents to lead games away, so it's not a threat to be discounted imo. There were a couple Glaceon that made piloting the Rayquaza team very difficult given Freeze-Dry and Glaceon's decent physical bulk, and there were a good chunk of Virizion players in the post-climb matches that gave me trouble with the Kyogre team.
(Meteor Beam)
There were a few players that opted for Meteor Beam Rayquaza to good results. Some Rayquaza seemed to be mixed attackers with Dragon Ascent, but I don't remember if they have Meteor Beam. There were a couple Aurorus brought to battle; it might have some use given its type advantage against some of the new Restriced Pokemon.
A couple players opted for Hoopa, and at least one of them ran away with the game. I'm not sure if it'll hold up against the Restricted Pokemon, but its superb Special Attack and small stature may grant it more steals during ongoing fights than its Unbound forme.
As for my experience with my climb, while I do think the overall power level and variety of threats to account for may contribute to this, I really did not like playing due to my very sloppy mistakes and the constant stream of competitive matches, which made me way more stressed out than I should be. The nature of competitive matches starting with a "Who goes first and gets punished?" type of deal followed by the cascade effect of "KO after KO after KO after..." or "player steals KOs with little contention then wins", combined with the absurd strength and big red targets of most Restricted Pokemon, is dissuading me from devoting more of my free time to this season, and I already didn't spend much time for the past two seasons either due to other reasons.
next. A set of Bulk Up, Drain Punch, Ice Punch, Earthquake / Poison Jab is poised to run over this meta.
: The number one threat against my team, by virtue of shredding Ampharos and Skarmory very easily with its STABs, while Mewtwo cannot tank it easily because of its low physical bulk. Stay away from Groudon-Primal and try to snipe it with Earth Power+.
: I saw that in one or two lobbies and Mewtwo has a hard time touching it. Wait for the opportune moment to snipe it when Shuca Berry has been consumed.
: I have encountered it in lobbies twice and both times it was more annoying than it had any right to be with no dedicated Ground-type on my comp. I've seen more Shuca Berry Trans which check an unboosted Mewtwo but Tran's not a real mon anyways. Idk boost up and EPower it.
