First off: if the idea is to figure out whether it is too OP or not, and you have the ability to check win %, why would you ban it the first season after the baton passer in question is part of an heavily-hunted event? Let it run, check the numbers, see if needs adjustment. Right now you based a ban on an incredibly poor usage, in a game without MMR, on the base of people's opinion. Not how it works my dudes, ever heard of suspect testing?
I do not think it is ban worthy.
I have played a Scolipass team (the famous and feared one that GlogS used to play, and a few variations of my own) for hundreds of matches with guildies and friends: in the right hands it tears people, in the wrong hands it gets destroyed. Guess what, that's the case of every team :D
Hell, when playing with my boy Sukres we even beat the ''broken'' Scolipede team played by none other than GlogS himself a couple times. So it is doable after all?
-THE GAME HAS NO MMR! I will never stress this enough. We are playing against complete random people, the (very big) majority of which has no clue what they are doing. No offense, its just the truth, time and practice will make everyone better. A batonpass team can sweep a ''noob'', term which I hate but whatever, in less than 5 minutes. I can sweep a noob with any HO in less than 5 minutes, same with any folk who reached 1.7k+ elo on SD, ladder on PRO, won regionals three time or whatever e-peen number makes you cool nowadays.
The teams I see around are not prepared for threats like Mamoswine, Serperior, Greninja...let alone some more ''deep'' tech that requires setup, and knowledge thereof. Lack of knowledge is the biggest culprit of people losing to this team.
-Manaphy...I still hear about people wanting legendaries banned, or Chansey, because ''broken''. Come on it is 2020, we have an awesome thing called Google with plenty of answers and guides for you! Truth is it's is plain and simple, although for some hurtful: skill disaprity 80% of the time, 9% is having the better pokemon IV/cheese strat, 10% pure crit and status RNG. Last 1% is when the server crashes ;)
I (mostly friends I am playing together with) murdered thousands of poor Manaphys at this point, poor little creature. He sets up Tail Glow and 6-0 you? Why did you let that happen in the first place. Think about how you lost rather than the fact you lost, or what to. That being said, an incredibly powerful Pokemon in the right hands. In the right hands.
-Togekiss is not as reliable as one might think, although yes incredibly frustrating: all it takes is 1 turn with a miss, not flinch, a single crit, a wrong move (heal belling instead of roosting etc) and the match heavily swings in the opponent's favor. It's an annoying pokemon for sure, but not because of baton pass. A Scarfed one can 6-0 you with flinches too, I've seen it with my own eyes. An incredibly powerful Pokemon in the right hands. In the right hands. Ok not as much, can be all luck too in this case.
Another, reason why baton pass is considered ''broken'' (it is only just really good!...in the right hands) is because many things that can destroy that tech...ARE NOT YET CODED!
I mean they were promised for years along side other cool stuff, but I personally prefer having a double cool sword on my character's back :)
-Volt Switch and U-Turn do not work properly, you need to select a pokemon before you see what the opponent does, which means adding prediction on prediction...absolutely crazy and the fact it is not coded after 4 years is not justifiable. That alone can gain you momentum against any batonpass or setup team and set you up to deal with it (or any other team, for that matter, yes even Chansey!).
-Substitute. Should I explain how oppressive that move is and how punishing it is towards a possible baton pass...or stall (you know, all the people complaining that Chansey should be banned). Code that and the meta will drastically change. No bans needed!
-Lunar Dance/Healish Wish etc: Trick Room would absolutely destroy the Scolipass team ft. GlogS. Of course, assuming skill level is about the same, which as I already pointed out rarely is. Cresselia easily eats +3 Manaphy with 0 investments, with could even force a 3HKO: Plenty of time to Trick Room and Lunar Dance to your sweeper and turn it all around.
Healish Wish on a pokemon like scarf Latias/Jirachi (faster than 99% Pokemon who receive speedpass from Scoli) can revive one of your priority pokes to have a second chance. You should have not let that happen for free in the first place, but in case, it's nice to have the option to recover from a game.
-"game is gen 7 based". No it is not. We miss a drastic chunk of the dex. PRO is PRO, or if you want it to be Sun&Moon, introduce all the possible pokes. I am talking about Tapus, Megas, Toxapex (special mention because forces Manaphy to run Psychic>Energy Ball, hindering its ability to deal with tons of mons), Lando/Thund/Tornadus, Keldeo...without talking about Z-Moves, which single-handedly can deal with issues in your team with 1 click... in the right hands.
Adding different sets on Legendaries was a god send, about time (and im thankful for that, really!), but not quite enough to make the game balanced, competitive or whatever. We are missing WAY too many things. That being said, even with all those things missing, Baton Pass can be beaten.
I appreciate the thought of trying to improve the game, I really do. You are just doing it in the wrong way. Some duct-tape on a leaking tube will not stop the leak :)
ps: if there is anything I, or my friends, can do to facilitate the coding/bug testing or whatever of missing stuff, please reach out to me. Game has seen no real updates in ages at this point, I lost more friends switching games to the new ones I've made at this point :(