These are just my personal thoughts and not something representing the council or anyone else:
I think the main issues with the tier currently are:
1.
Several strong threats that can be difficult to stop:
I'll be honest, I wrote the rest of this post and then tried to write this part, but I wrote so much already, that I'm gonna keep this one short. All the above mons are very good and can be overwhelming at times, but they're closer to being strong individually rather than having a negative effect on the tier. Banning them all probably does help, but the issues with that are that it takes too much time, because none are on the level of being quickbanned (this is probably debatable), meaning that multiple suspect tests are the only way, and then that each one individually does not necessarily have a strong effect on the tier in terms of teambuilding.
2.
Gliscor, Gholdengo, and their effect on the metagame:
Gliscor is a phenomenal mon no matter what set you're running and that's because it has the tools to threaten anything (Toxic, Knock, Off, Spikes, SD) while also being very unkillable. The number of pokemon that can safely switch into it and threaten it back is very small (Clefable, Corviknight, your own Gliscor, Air Balloon Steel-types), and that's ignoring that most of the time, you'll probably have to slow pivot into an Encore mon or something like a Water/Ice-type or Tera Blast mon to force it out. Add in the option for Gliscor to Tera and it might just be literally impossible to 1HKO depending on what type it becomes and what mons you have.
I think Gliscor has counterplay on paper, but in practice you never actually know if your counterplay will work until you learn what set Gliscor has, and if Tera can flip the situation to favor Gliscor or not. Air Balloon Steels work until it reveals U-turn/Knock Off, your own Gliscor works until they reveal SD or slow U-turn, and then everything else hates Toxic + EQ coverage and will fail to 1HKO back naturally, or after Tera (like Tera Water letting you wall Greninja). If you do bring a strong mon like Choice Band Rillaboom, that probably works, but you have to deal with not only Gliscor getting to scout what move you choose with Protect, but your Rillaboom is also on a timer due to taking hazards, which there will probably be a lot of thanks to Gliscor putting them up, and Gholdengo for keeping them up.
I feel like Gholdengo is annoying for 2 reasons, the first of which is that it is incredibly good at denying hazard removal, especially with an Air Balloon, and then then the second is that it is very strong offensively. The second one is what actually bothers me more, because like Gliscor, Gholdengo can be very difficult to 1HKO normally, and then when you add in Tera, then it's probably impossible in most matchups. A bulky Tera Gholdengo will most likely eat any hit from offensive mons, and then it will wall and set up and sweep bulkier teams, and there's not much that can stop it at that point. You usually have to either hope its coverage is unideal for that matchup, or that you're able to PP stall Recover or wear it down through various means. There's also the issue that defensive answers like Ting-Lu end up being fake checks because you are not only prone to coverage/Trick, but the moment Gholdengo Terastilizes, your only option is probably to PP stall Recover and hope for the best. Kingambit is the best answer, but it has to deal with Hazards, no recovery if it has Boots, Shadow Ball/Dazzling Gleam/Make it Rain chipping over time, and the occasional Focus Blast outright killing Kingambit on the spot. Sometimes Kingambit and Ting Lu can handle Gholdnego, and sometimes they can't, but Gholdengo in general requires too much effort to handle compared to other mons in the tier.
Going back to the first reason (denying hazard removal), I think with the additions of Ribombee and Gliscor, the hazard issue is starting to feel very upsetting, because Great Tusk has to go through a lot of trouble just to get Rapid Spin Off (eat a Toxic from Gliscor, or pop Gholdengo's Balloon first and then EQ it later on a switch), Corviknight can't Defog on Gholdengo, and then that just leaves your options as using Cinderace's Court Change, or just running a lot of Heavy-Duty Boots on your team. The last one (Boots) is definitely the current go-to option, and while the item is generally great, it does feel forced and anything that feels forced to a heavy extent is probably not healthy. I think this doubles as a benefit to Gholdengo and Gliscor, because like I mentioned earlier, you need something really strong like Choice Band Rillaboom to 1HKO either one, and Gholdengo encouraging Boots rather than Choice Items means that you either need good coverage, or something that hits hard enough with a Tera boosted attack. It's very doable, but not enjoyable personally.
3. Tiering a temporary metagame due to the DLC structure:
Everyone's allowed to have their preference for how this one is done, and it's definitely been a challenge for the council this generation with multiple releases (gen 9 release in November, Home in June/July, DLC1 in September, DLC2 sometime between November and March). Under normal circumstances, or after DLC2 for example, it's preferable to give time to see how the metagame evolves to determine if something ends up being fine or if something gets out of hand. However, for temporary metagames, you have to ask yourself, do I want to tier the usual way, or do I need to tier a little more aggressively/quickly, or should I be patient and not go overboard with it.
I don't think there's a right answer to my previous question, and I say that as someone that would prefer more aggressive tiering in temporary metagames. Sometimes people will find counterplay to stuff that works out perfectly. For example, I voted to quickban Garg at the start of this generation, but then a few weeks later, Covert Cloak started to grow common, and Garg became a lot less broken. People will continue to come up with creative ideas to serve as counterplay to existing threats, and it's good and healthy to give time for those ideas and tier development to happen.
The final part to this probably the main problem, but if we tier normally, then that would mean targeting the big brokens one at a time until the metagame is stable, but for our current case, we have A LOT of very strong pokemon, and then we also have the biggest culprits in Gliscor and Gholdengo. We can test Roaring Moon and then Manaphy, and then Sneasler and whoever, and we'll probably be in December by the time we're done with 3 or 4 back to back tests. I don't think needing that many tests in a short period of time is a healthy idea, granted it's closer to necessary than good, but I would personally rather look into Gliscor or Gholdengo first because banning either of those is what will lead to the tier actually changing in a significant way. I think we need significant change, and our only options are banning certain pokemon, unbanning something from Ubers, banning hazards, or banning tera. I don't think the latter 2 should be considered in general, especially before we see what DLC2 brings us, so that narrows down our options to focusing on pokemon currently in the tier, or possibly something from Ubers. I don't know which Ubers would be worth looking into without getting immediately banned, but if we were to take action on something like Tera Blast. then there would be a lot of mons that could be reintroduced from Ubers to OU, like Volcarona and Regieleki. Tera Blast was already discussed in the
Tera PR thread a few months ago and would probably be the only type of action people are comfortable with in regards to action on Tera.
Banning something like Gliscor or Gholdengo is what I believe could be a step in the right direction, and it would be a worthwhile step compared to taking 5+ suspect tests in a row for a watered down version of the current metagame. However, that's just my take on wanting to make the current metagame healthier than what it currently is. Letting it continue as-is or even unbanning something from Ubers for a few months is technically fine too. There is no "right" option because it comes down to personal preference, and my personal preference is to target the bigger influences on the tier in Gliscor and Gholdengo immediately.
Again, these are just my personal thoughts and not what the rest of the council thinks. Have a nice day.