I'll start off by saying I actually think the BW metagame is in a good place right now, the teams and games in SPL were by-and-large super engaging, though I may be biased as a helper of Fakes who just piloted our teams like a cyborg every week.
My tiering priority remains the same as after the January suspect:
Cloyster - This mon is straight cheese, part of the reason I found SPL was so good was the fact that people weren't fishing with this guy but I'm confident its time will come again. We did a lot of building with the Mixed set which is really absurd, it can run almost no speed to pump up both attacking stats and still be fast enough for what it needs. Almost all the checks / counters people raved about in the suspect thread get dropped by this thing - Keldeo, Slowbro, Forret, Magnezone, Reuniclus etc just drop to the special moves, its a really dumb mon. By the end of the tournament our approach to Cloyster was just to tech a slot to deny set up on every mon (including some ludicrous stuff like EPower Lando which is ass tier but kind of necessary on what we ran) because if you aren't doing this, then you're likely at the mercy of its set diversity if you ever get slightly out of position. It exists purely to try and generate autowins off of what should be safe Pokemon clicking safe moves (SR Landot and Gliscor) and I continue to find it a pain to have to Cloy-proof my teams, on top of the actual good Pokemon I need to cover.
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Regarding other stuff in this thread:
Latios and Excadrill I think are necessary evils. Latios is a glue support mon to me right now rather than some unstoppable offensive threat - sets like Specs are a luxury that most teams can never afford to run because it gets so much value out of being unchoiced. I think, if anything, having a one slot revenge killer to Keldeo Thundurus Garchomp Terrakion, which is also Spike/Ground immune, and a sturdy Water/Fight resist, is a huge teambuilder enabler rather than restricter.
I'm open to some kind of Latios suspect but I do worry that we'd be trying to strike a sweet spot between replacement Latias being just good enough offensively to keep Keld/Thund in check, whilst being a sufficient enough nerf to where PsySpikes strategies aren't overbearing. Thats a
very narrow needle to try and thread and its very possible we end up in a situation where either 1) Latias is just too weak to really be decent counterplay to Keld Thund or 2) we realise actually that our issues with Latios go beyond just its SAtk stat and so much of its role is about support of other Psychics, and we continue to have the similar issues even with Latias + Spikes + Reun/Zam.
I would 100% be up for a suspect of Sand Force, this is something we've discussed in the discord this SPL. Excadrill is a positive influence as the only decent sand spinner in the meta but it is just ever so slightly too strong + its wacky HP stat means it gets huge amounts of versatility regarding EV spreads. You can run fast Gliscor and still lose to SD Excadrill because its crazy stat spread allow it to invest decent amounts in PDef at times, or you can attempt to rkill it with Latios only to realise its SD with like 200 SDef. Its just too strong + crazy typing + EV spread / nature diversity which is hard to determine from the calculator. If you go back to Ojama's initial
unban Drill thread, the proposal was to unban Mold Breaker Excadrill only and I can assume the reason this didn't go ahead in this way was because it was not believed Sand Force would be overbearing. I think we've got a sufficient body of evidence that Sand Force actually turns a great support Pokemon into a borderline suspect in its own right, and I would like to explore any options we could to enact the initial vision that the Excadrill unban proposal had - give us an Excadrill that cannot offensively abuse Sandstorm.
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The only other Pokemon on my radar would by Thundurus-T and Reuniclus. Thundurus-T's low winrate points to part of its issue, this guy's entire existance is "uncounterable if I hit my moves and/or get secondary effects", its literally just playing games with 30%s vs a hyper specialised killing machine. Thund-T has every tool in its arsenal to be an elite offensive mon from boltbeam coverage with 145 satk, nasty plot and agility, uturn, 30% paralysis chance to deny pivoting around its STAB. Its purely nerfed by the consistency of its attacking moves, which is incredibly unengaging. Very often you get into unavoidable midgame states vs this mon where its like, ok well i need him to not hit 3 70% acc moves in a row, i need him to not para the latios on switch, i need him to not tank this latios meteor after SR (most bulky spreads are ~50-50 on this), everything about Thundurus-T just lets the odds play the game and it never feels fun.
Reuniclus in contrast has had an insane SPL and continues to reinvent its structures every 2 years, now with paralysis-focused HippoClef builds. I'd probably argue that a lot of the issues people blame on Latios rn are actually the result of Reuniclus. I think as we get more optimal building and playing with Reuniclus we realise how poor some of the "answers" to it are - Chople Tyranitar without spin support is simply not reliable Reuniclus counterplay, Skill Swap is an 8 PP gimmick that gets burned out in passive mirrors, Encore is also 8 PP which Reuniclus can pretty easily outlast, SD Gliscor loses to CM Ice etc. We saw multiple games in SPL where the optimal win path was simply to paralyse Reuniclus and set-up your own Calm Minds alongside it which is fine unless... both players are going for the same endgame, and then its just degeneracy. This win route vs Reuniclus is remarkably common and the only reason we don't often see it as an issue is due to how rare Reun mirrors tend to be. I love abusing this mon + working with it in the builder but it is objectively really really silly, and is the true root of the Spikes + Latios issue, not Latios itself.
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tl;dr -
priority - suspect Cloyster,
maybes - consider if there is any way to suspect Sand Force, consider Thund/Reun,
don't even think about deo-d fml