Alakazam B -> B- or lower
When was the last time anyone actually used this thing on a serious team... Sure, sash counter is cool in theory but its far from splashable, and is its only niche. There are minimal reasons to ever use this over something like scarf Lele as a revenge killer, while it also lets in mons like AV magearna and celesteela for free. In general, this thing is completely irrelevant in OU.
Terrakion B -> B- or lower
This mon was ranked for its scarf set, and its scarf set is completely outclassed. Even infernape, 2 sub ranks lower, is superior to this mon as a scarfer. Infernape offers better pivoting abilities, a much better move pool and beats both volc and mage more consistently. The majority of its offensive sets, such as SD rockium, have no reason to be used over landorus t.
Rotom w B+ -> B or lower
This thing fails at almost every role it had in oras. Its a shit ground check, can't switch in more than once or twice to gren or rain abusers, and tang and venu can come in for free on any of its moves.
Gastrodon B- > B
This thing is honestly really solid on teams such as the ABR team recently used on ladder a lot with kartana, gastro, megatar etc. Its honestly superior to most of B- rn, like I would never put this mon in the same category as some ultra niche mon like mega sharpedo.
Mega Manectric B -> B-
This thing is honestly terrible right now. Mega venu shits on it, has extreme competition from koko, and loses to almost all common play styles right now. Its deadweight vs rain because of pert, dead weight vs balance because of mvenu and clef, obviously dead weight vs stall, and vs offense it does little that koko couldn't, outspeeding ash gren is nice, but its a mediocre check for it anyways because a few rounds of hazards and it dies to shuri anyways.
Amoonguss B+ -> B or lower
There is more or less 0 reasons to use this over mega venu. Usually in a game at the very best it can sleep one mon and then become set up fodder.
Deadweight vs any fat play style, pressured too much by offense. In general just bad lol
Tapu Fini B+ -> B
This mon is pressured way too much by tspikes and hazards in general, struggles vs stall now that tang is run frequently, as well as vs pink mons stall where zapdos is used. In general, more of a Digimon
Manaphy B- -> B
This just rose but its so dominant on both veil and bird spam that it fits much better in B. Honestly a bit of a crime to be ranked next to mons like zard x etc
Hawlucha B- -> B
A little less sure on this but it is very threatening on rain and still feels just "better" than the rest and closer to B rank. Just gonna put this one out for discussion or something
Jirachi B -> B-
This faces so much competition as a bulky steel type from ferrothorn, celesteela, magearna etc that its not worth using. Has minimal usage for a good reason.
Slowbro B- -> C+
This thing literally does nothing lol, shittier toxapex that loses to gren mage koko all when they're at their best rn
Mimikyu B -> B+
HO is at its peak right now, and this is a staple on almost all HO builds, in general think it fits better among the B+ mons. Super good emergency check for HO, and red card has been seeing some recent usage as well
Dragonite C+ -> B-
Because of its popularity on bird spam, I think it deserves a rise. Fly z dnite works very well in tandem with mega pinsir to break down common checks.
Kabutops and Omastar -> UR
Rain is pretty formulaic right now and neither of these mons fit. There is minimal reason to use either of these when mega pert, kingdra and ash gren are so good, there really is no place for either of these mons.
Breloom -> UR
I think this was talked about earlier, and this thing absolutely hates mega venu rising, and really can't do anything in the current meta.
Latias B -> B+
This mon is one of the best scarfers right now, and while the power difference from latios is a little noticeable, healing wish is worth it in this meta. This was touched on earlier so most of what I could say has been covered.
A few other mons that I think could rise but not sure on are Kartana, Kyub, Lop but I'm about 50/50 on those, I think they're sort of between B+ and A- right now.
Im also bad at writing descriptions but I think most are pretty self explanatory.
Edit: Also unrank gliscor lol it does absolutely nothing better than any of the common grounds do. In general doesn't beat a single common archetype