Hello everyone !
I'll take inspiration from
UnnerfTalonflame's format and share some teams to use them as springboards for remarks on the meta. I can't provide the full thought process behind the manufacturing of every one of these since I built them a while ago, but I'll outline the main points.
Teams

Here's a team I built around this bulky Regen Landorus-T that I really wanted to try. If i remember correctly the spread is for Band Terrak on the physical side, for Scarf Blace on the special side, and the atk makes sure it beats Intim Corv with Smack Down. This set can pretty much make progress in every game for one reason : the Regen mons can't really come in on EQ, or they take over 40 in Pert and Fini's case. That means they have to go Zapdos and take Toxic, or go Corv and get Smack downed (worst case when using this Lando), or some physical wall like Mew and get U-Turned on. It's also really good at soft checking pretty much the entire tier, which helps since there's been a trend towards choice breakers. Then I had a Regen Ground (so no Pert) and a defensive flying type (no Corv), meaning my Weavile answer had to be Fini (ban Weavile). This Arcanine's good af. The Chomp exerts a lot of pressure on most teams, especially since opposing Finis often end up taking a Lando EQ/Toxic or Arc Will-o, meaning they usually can't come in for free. Obviously you want to avoid clicking Dragon Rush but you sometimes have to unleash it on a bird. Lots of momentum, sometimes the team just wins instantly on matchup with Lando or Arc or Zor ; a lot of flexibility.

The lack of Poison types in the tier encouraged me to find a reliable T-Spiker, one that could beat every defoger and still have nice defensive utility. Dry Skin Nidoqueen is pretty much the perfect T-Spiker. It threatens bouncers and Fini with Poison Jab, it threatens potential Poison Types with EQ, and it Taunts Corviknight for free. Dry Skin over Water Absorb lets it take Zapdos Hurricanes and potential Barraskewda Drill Runs quite easily. It seemed to me that the most threatening mon with T-Spikes up would be Cobalion, since its main answer currently is Swampert, and potential other Regenvesters. Furthermore it is a very reliable rocker, which I highly value. It also occured to me that T-Spikes being up would force Defogs from the opponent, and would consistently win the hazards war (given Nidoqueen has also very good defensive utility and plenty of opportunities to come in) ; which could allow the use of RegenVest Inci despite its rocks weakness, cause this mon pretty much walls every special attacker in the tier except for Primsea mons (Zapdos, Prima, Inteleon, Koko), which all lose to Nidoqueen. Primsea Zapdos isn't only broken, it's also very good with T-Spikes up, so I added it since it fit well. Weird spread for Zarude and other stuff iirc. Then Mew, and Fini because Weavile. DTail on Mew is important I think, since there's been a trend towards random winconds with slow setup (damned
motherlove). Heal Bell to heal Toxics from Heatran. The team is slow overall as you noticed, but it's very solid and applies a lot of control over most games. The Mew, Fini and Zapdos sets are flexible depending on the meta.

Remember my old Psyspam team ? Here's a new one. I tried a lot of structures, and this one is as close to optimal as I could get. Corv is definitely the best terrain setter ; it's physically defensive since the sweepers are rather bulky on the special side here (so you force your opponent to hit on the special side and sweep right after with the +1 Spdef Berry). Bounce Sitrus Swampert is godlike. 80% of games you lead with Corv and go Pert on Rocks or whatever, and Flip Turn to try breaking holes. Usually games last below 25 turns so you don't need lefties nor Regen, you just need hazards away for Sash Zam and Cinde, as well as the two Unburden breakers. Speaking of these, Psyshock on Necrozma is necessary to weaken Blissey and then win with Hydrei in a lot of cases (or the contrary : weaken them with hydrei and win with Psyshock Necro). Photon over Expand is an option, but the extra power is nice. Scarf Cinderace feels just like Band tbh, it's ridiculously strong ; but here it also outspeeds everything. Sash on Zam brings the extra surprise effect. Guard Swap is an option over Knock to avoid getting 6-0d by demon Mew. Sometimes you run into losing matchups like Flash Fire Mandibuzz + Hydreigon counter but it's life. Otherwise very reliable and easy team to use.

Sadly I discovered No Guard Xurk right before Sleep Moves Clause was implemented. With Hypnosis this mon is an immense threat. Without it it's still very good so I'll still share this team. I wanted a special attacker with a very spammable STAB that could take advantage of the opponent's special walls being Paralized by Xurk, and that would also be fast. Inteleon fit this role perfectly, so I had my core. Then I added Bounce Blissey because it enjoys having a Primsea mon in the Back to generate 50/50s against Heatran (especially DLand). Having such reliable Tran counterplay made Fini all the more appealing (I'll talk about Fini and Weavile and why the former is in 3/4 teams). And the fun doesn't stop, since I ended the core with Regen Gapdos (which allows in Xurk and Intel very well) and most importantly
Klutz AV Trick Palo. This isn't a meme, it's a reliable Rocker since Trick massively cripples (kills pretty much) the opponent's bouncer if they have one, as they'll definitely switch to it ; but also their Defoger, and the next time you'll get up Rocks they won't be able to Defog. This is made possible because Palossand doesn't need any extra ability to deal with the mons it's supposed to counter, like Terrak and Koko. A surprisingly well rounded team given the unusual things it contains.
Metagame


I think Swampert is a better Regen Water type in and of itself, but if like me you dislike using Intim Corv and Coba, it's kind of forced in every team. The assertion that Weavile allows sufficient freedom in the builder is unearthly, as well as the one that you can avoid letting it in with correct play. You cannot. Even teams that feature innovative defensive cores with Scarf Regen and all ; a Knock, a Trick or some kind of crippling very quickly offer room for Band Weavile to get it over the course of a game. Most of my point is already argued before.

I hate Zapdos. It's broken. It can
reliably 1v1 its best counters with confusion/para/Toxic from team support. Reliably. Playing around Modest Primsea Zapdos is a daunting task, it's not really possible in a lot of scenarios. Stuff like Silv-Dragon, Blissey, AV Pert, they lose. I hate it.

Zarude is definitely securing itself as a top5 mon. The Psychic immunity, the priority, the terrain support, the pivoting, being a Swampert check (this is big, lots of teams are very weak to Pert), everything is great about it.

Heatran is
a bit overrated in my opinion. Yes, it can make progress in any game, but 1) most teams feature a special wall + a Primsea user, forcing it to come multiple times in order to truly break through, 2) the gameplan that comes with it is usually quite obvious at team preview, offering ways to circumvent it (for example if you see tran + blace you'll preserve your AV pert and go Primsea Zapdos on Tran). Still a good mon, but
The Number Man should definitely diversify his building style, as I think a good prep can easily beat it. For example (and
UnnerfTalonflame asked for Tran switchins), Magic Guard users like Arc, Moltres, Volc or Latis straight up wall all Tran sets.

Scarf Aelf is incredibly good. Provides a lot of flexibility gameplan-wise. Makes you safe against Triage users as well as very fast sweepers like Kommo-o. As you can see (same for Zapdos, Zarude and others), some kind of defensive utility is what defines the cut from a top tier breaker (like the ones I mentioned) to a fine but not as great breaker (Blace, Terrak, sflo Lele, etc.).
UnnerfTalonflame's team, as well as the teams I posted show this well. This is the reason why Terrain and Primal weathers breakers are so good.

(Click) This Terrakion is the best one. Ohkoes both Mew and Corv after Laser Focus. Can only be stopped by winning multiple 50/50s if you can't prevent it from coming in. Pairs very well with Scarf Azelf. Crits in general are an under-exploited strat.