OMASTAR: BAN
For omastar, this thing is super duper ridiculous. There are no such thing as sure-fire counters to this thing, and the mantra that you can prevent it from setting up in order to beat it has never been less true than as of this generation. Access to a weak armour+meteor beam combo make it the best uturn deterrent in the history of pokemon (behind eject button sableye ofc), and give it more than enough headroom to finesse its way through offense. The standard balance archetypes will have a much harder time preventing the setting in the first place, or indeed finding the room for an adequate revenge killer of which there is 1 in my opinion. Building wont super be benefitted from banning this, but the playability of the tier will for sure.

KINGLER: BAN
Kingler is similar to omastar in a couple of aspects. Its ability to provide both wincons vs offense and balance in the same spot as well as the bulk needed to get those settup moves off makes it quite clearly a top tier threat. The thing with kingler, even though it can be argued omastar and indeed others are better late game sweepers is two fold. Nothing beats Kinglers outright power straight out of the box (given its ability to change moves also), but probably more importantly, nothing in the tier is even remotely similar to kingler. So you find yourself in this complicated space where people will literally use garbodor, ferroseed etc as their kingler counterplay whilst simultaneously praying that they can outplay once the damage has been done. Access to knock off makes it even more scary for any balance teams to even consider taking it on more defensively. In this case, I think the building of the tier will be suitably benefitted, rather than the playability per se.

CLAWITZER: DO NOT BAN
Clawitzer is no doubt a scary ass breaker with oodles of power. That being said, more power than alternative options to me isn't a significant reason to ban it. If we start seeing problems with the likes of lanturn being incapable of checking it, then Id want to reconsider this, but for now I think its fine. The impact of banning it on the teambuilder wouldnt be too large, and as a slow breaker, the playability shouldnt be sacrificed.

TOXICROAK: BAN
This thing wildly differentiates itself from the other fighters in the tier by providing valuable defensive utility as a water absorb mon as well as having a unique typing, but more importantly, capabilty of running a special set which absolutely BODIES the tiers current fighting type resists. This often forces builders into a distinct corner where they prepare for fighting types and prepare for toxicroak completely seperately, and in game, forces players to make split second 5050 judgemental calls based on if the opponent is weak to omastar for example. I believe these aspects make toxicroak a major problem in the teambuilder, as well as affecting how the tier is played. It should be noted that there is a reasonable anti-ban argument if omastar ends up being not banned, since whilst its one of the only things with access to vacuum wave, makes for a nice check to it, but in this universe, I dont see a way where omastar doesnt get banned. This things influence on the tier is arguably even greater and banning it would lead to instant dividends both building and playing.

RIBOMBEE: DO NOT BAN
I'm still majorly on the fence for this thing. My main experience has been vs ladder using it, who use non-sets like specs and others, but clearly a boots qd roost set seems incredibly juicy at the moment. The instant cleaning potential from its huge speed makes it one of the most consistent cleaners in the tier, but is consistent equivalent to broken? Meh. I dont know still. I haven't seen enough of it. I will be keeping my eye closely on it though, with any matchups particularly interesting. If the above bans do happen though, an expected resurgence of steel types might be predictable to better take this on.