Played about 30 games on the ladder, and while my experience was um, interesting (In my first 15 games istg i got crit 3 times every game and missed every move you could, fuck meteor beam) I do wanna give my thoughts on leo.
I think people are heavily underestimating this mon, partially because yes, it can't beat every mon with a single set, but it also has so many sets and can customise its movepool to beat its counterplay. I also think that it doesn't really bring too much benefit to the meta besides a kyurem check which like, ig? Kyurem's broken days are long past it, and this is coming from a former kyurem ban lobbier. Like, dnite is beating your ass even if you use sunsteel (which is a move leo shouldn't use, I'll explain more later), screens it is a great abuser of and with mons like goltres, it doesn't even guarentee it will do well into screens, while webs is mostly middling and once again, it can abuse itself. It also breaks fat, but are we really still coping that fat is unhealthy? Fat teams are firmly just 'good'.
But anyways, I'll talk about the sets that I've tested/seen:
Teleport sets: These are bad outside of TR, where they are godly. On normal teams, this is just so mediocre and wasted potential as it is incredibly passive and just not threatening, and you need like, 6 moves to actually function. On TR teams, this is such a reliable setter, you don't even need sash ngl, since you just face tank any one hit. Specs rai dark pulse does 77% max to full spdef leo while to the same set, tusk headlong does 92% max. You won't die and thus can get off the tr and either kill yourself with steel beam while dealing decent damage, tport to the abuser safely, setup a future sight etc. The item is also pretty flexible, mental herb stops taunt, red card can phase out sweepers/attackers, a berry of some kind can allow you to live even boosted attacks etc. TR is already a pain to deal with, and IDT leo helping it by being an amazing setter is good for the meta.
Banded: This set is good, but people will use the one move you shouldn't. DO NOT USE SUNSTEEL STRIKE, IT IS ASS. Genuinelly, aside from like, hatt (which you 2hko with flare blitz and doesn't really wanna switch into leo anyways), what does it hit? Clefable is 2hko'd by psyfangs, geezing is smashed by it, garg takes 40% from psyfangs and eq/cc heavily chunks it. Kyurem hates taking psyfangs. Its just not worth. Especially since every other move hits something important. After psyfangs and knock, it feels decently customisable. I prefer flare blitz third since it hits most steels aside from heatran super effectively, hitting ghold gambit and corv is great, but cc and eq are also decent. The fourth moveslot can be any of wild charge (hits bulky waters like mola and dozo for large damage), stone edge (hits the status birds), a secondary steel move to cover the other steels you can't hit, or morning sun to keep it healthy across the game. It also is a breaker that checks kyurem and fairies, which is great. Bit difficult to fit, but its not the worst thing in the world and it more then rewards you.
Calm Mind: This I think is the best set, and its honestly pretty powerful. CM+2a with morning sun is pretty busted behind screens, as its able to trade exceedingly well at worst, while being an incredibly sweeper. The best attacking moves I think are flame+psychic move. The only mons that can beat you are ttar and ting lu. The latis have to specifically be trick to beat you, otherwise they are just setup fodder. Heatran just loses to you behind screens, even if it is taunt (you get to +2 then proc wp, which then makes sure that psyshock 2hkos while heatran does jack). Hamu has to be specifically AV, otherwise it doesn't do enough back and +3 flame 2hkos it. Hydreigon has to be NP otherwise it just loses lol, and gren just does jack to you. Ttar only beats you if its roar spdef, otherwise it literally just loses to you and ting lu isn't too hard to overwhelm by overloading it with stuff like goltres while flame does chunk it a decent amount if they proc wp (which if they wwind without proccing, then it gets chipped and potentially burned, which is ruinious). Psychic stab depends, I prefer psyshock to beat opposing cm mons while psychic can help against dozo and shit. But really, this mon just trades insanely well, at worst, 1v1 trades with something, but typically either trades 1v2 or sweeps. You can swap out flame for focus blast, which makes you a lot better against the darks, but worsens your mu into ghold and psychics while having to be focus blast.
Mixed LO: Haven't really used this, but from what i've seen, its merely alright. That being said, stop using thunder, use tbolt. You can knock av mola and the accuracy issues are not worth it. I also don't like how it lacks longevity if it wants to hit as many mons as possible, but maybe somebody makes it work better.
TLDR: Mons broken, stop using tport on non tr teams, run banded and cm, mixed LO is prob also fine.
And finally, here are the main teams which I've been using solgeleo on:
https://pokepast.es/331388a77f529d52
https://pokepast.es/936c09613c75082f
https://pokepast.es/a2043d15cac380d1