Clawitzer: do not ban
i've been on the fence about this mon, but as it stands i don't believe that it's too much for the tier to handle. yes, it hits hards and has no real safe switchins outside of somewhat niche options like articuno and spdef frosmoth, but it's also rather slow and easy to pressure. it's very, very similar to how drampa was in november meta, or, for a more recent example, virizion; all threats with no real switchins thanks to their splendid movepool that you can revenge kill or offensively pressure rather easily. what differs clawitzer from these two, though is that it trades versatility for being somewhat harder to switch into as it's usually better at freely clicking moves. however, all of the moves it can lock itself into can all be taken advantage of by threats like toxicroak, ribombee, heliolisk, alolan exeggutor, scrafty, and silvally-ghost just to name a few. it's a very solid balance breaker, but it has a considerably harder time against more offensive teams; breakers should be able to, well, break, and i don't think clawitzer does that overwhelmingly enough to warrant a ban

Kingler: ban
from what i've seen, and from a decent amount of games i've played either using or facing kingler, i really despise this mon. it doesn't have reliable answers outside of tangela or very uncommon and unreliable options like lurantis. other resists only work short-term and can all get overwhelmed very easily like druddigon and jellicent as they often have to do other things. agility also means it can always 6-0 any offense team after some chip on tsareena / drud / whatever grass or dragon they're using, which isn't hard to achieve at all. i think it's mostly worrisome because it can pretty much just run over offensive teams while also having a very solid balance mu. kingler also has the movepool to adapt to whatever answer is gonna start popping up - answers that, btw, generally struggle in the current meta. i just don't see kingler as being a healthy presence
Omastar: ban
Omastar's just too reliable at what it does; without a scarfer like smallgeist or rotom, you often end up struggling immensely against it; choice scarf togedemaru is a nice revenge killer, but it's also setup fodder for omastar, as zing zap doesn't ever ohko at neutral. what all of these have in common, though, is that they cant ever revenge kill omastar after a weak armor + shell smash boost, which really isn't an unrealistic scenario at all, and it tends to happen quite a bit. it does not have any reliable counters, and it constantly forces you to play differently and perfectly and to keep your revenge killer, be it a scarfer or a priority move user like toxicroak. this wouldn't be an issue if omastar could only really setup once in a game, but in my experience it actually doesn't particularly struggle to setup multiple times in a game, which is especially true if they use any physical choice-locked pokemo
Toxicroak: do not ban
toxicroak is for sure an annoyance, but i think what holds it back from being broken is its really bad bulk and constantly wanting 4 attacking moves. nasty plot sets don't have any solid answers outside of spdef garbodor, but it's actually not that easy to get setup opportunities and it doesn't hit that hard before a boost. it also struggles against a lot of faster mons without (or with in some cases) priority, like scarf pass, scarf mes, ribombee, and archeops - talonflame leaving notably makes it easier to fit earthquake on passimian. without focus blast / knock off, it has a considerably harder time getting past stuff like gigalith, cofagrigus, and jellicent. this, from my experience, often leaves it wanting both pretty much every other game. it's a really scary breaker, but chances are it's always gonna struggle against something 

Ribombee: do not ban
i think this is worth keeping an eye on, but as of now i don't see it as being too much. quiver dance sets are especially scary, but defensive answers like gigalith, spdef togedemaru, steelvally, galarfisk, charizard, and even centiskorch, are all solid options that are not hard at all to fit on teams. it's a bit more annoying against really offensive teams, but those can still often fit a fire-type or a steel-type that can switch in once or twice. imo the other two sets are fine, choice specs is good but easy to pressure with entry hazards - locking yourself on non-stab psychic can also be costly, and offensive support is just extremely weak and from my experience it's a fine offensive pivot, nothing more