There has been a lot of discussion about how Slowbro centralizes the tier in the Discord and other platforms, but none of it has made its way to the NP thread. I've been very vocal about why I believe Slowbro is not healthy for the tier, both in the builder and in practice, and there are two key reasons why.
The Dynamic of Tera Poison Slowbro
Whenever I see people talk about Slowbro as a manageable threat, they usually cite the amount of things that can pressure Slowbro pre-tera, and the ways that you can punish Slowbro for clicking tera at a bad time. These are both correct points, but the dynamic this seems to miss is that Slowbro exists in both states at once as a potential sweeper until the Slowbro user commits to a tera. Plenty of checks such as Magnezone, Muk-Alola (which isn't a great check regardless), Toxic pokemon, Brute Bonnet, Basculegion, etc. lose to Slowbro after tera. There's also a host of pokemon that can offensively pressure Slowbro AFTER tera (such as Psychics and Grounds), but are not equipped with the tools to handle it beforehand.
What this means in practice is that every team needs to have at least one check to both Slowbro before tera, and a hypothetical Tera Poison Slowbro. BOTH of these checks need to stay alive while the Slowbro user has tera as an option, as losing one will allow Slowbro to start setting up and force uncomfortable play from the opponent. Sometimes you can fit these Pokemon into one check, but they typically start to flounder after Slowbro gets a couple Calm Minds, require getting a key turn right such as a Trick user, or are simply extremely niche outside of the Slowbro use-case (Cacturne has been discussed in the Discord a lot as of late). This is all compounded by the second point:
Slowbro Outlasts its Checks
This seems like an obvious point to make, but with Regenerator and its massive bulk, there is almost no risk to switching out of a potential sweep at any time. Unlike other setup Pokemon, its not a threat that you are able to limit to 1 or 2 setup opportunities unless you build your team specifically around not letting that happen. In addition, since it threatens a sweep every time it comes in, its Scald becomes way more potent as an option to either completely shut down checks, or to put the opposing check on a timer that it will be able to outlast. Take the example of AV Magnezone for example. It is consistently able to switch into Slowbro's Scald, taking about 20%. But once the Slowbro user lands the burn, the clock starts to tick faster and puts the Magnezone user in a rough spot.
A lot of the ways to check Slowbro assume that you are dealing with a 1v1 situation in which Slowbro is setting up and the incoming Pokemon is able to completely shut it down, but in a 6v6 format, Slowbro is the most flexible pokemon to be a sweeper. It is quite literally rewarded for stopping its sweep with more HP back, ensuring that it will come back in to ask questions of its checks again. This, paired with the fact that Psychic Noise can be used on the switch-in of even niche defensive pokemon that can check Slowbro and have recovery such as Milotic and Quagsire, means that Slowbro is positioning itself the entire game for a sweep while being on the field for much more time than a typical setup sweeper should.
Side note, but people often make fun of people using Slowbro as a Slowbro counter, but I'd like to ask the question: why do you think that is? That's because Slowbro happens to be one of the most effective counters to Tera Poison Slowbro, covering one of the two checks that are absolutely required while running a broken Pokemon at the same time.
I don't believe that any meta that so heavily rewards the use of a Pokemon is healthy. It is the best defensive pokemon, it is the best setup sweeper, and it assumes little to no risk at every stage of the game. There are situations where you are able to fish for Scald burns against would-be checks because you are at a high enough percentage to take a hit, and that is enough to depend on Regenerator to heal you back up to full after a couple sequences. The stranglehold that Slowbro holds in the builder is precisely why creativity is being limited, and there's only so much you can do for one pokemon when you have an entire meta to cover.