Got a couple noms in the B ranks, should hopefully provide some discussion not about Mega Pidgeot.
B+ -> B: Salamence had a lot of hype after its Flyinium Z set was discovered, and it was pretty good, but it's fallen off as of late. It's easily handled by common fat mons in the tier, particularly Lando-T which is on 50% of teams, Celesteela, Skarmory, Ferrothorn after you burn the Z move, etc. On top of that, Salamence requires lots of support when placed on a team. It's weak to Stealth Rock, so it needs hazard control if it wants any hope of sweeping. It also pretty much needs Magnezone in order to be effective, or some way to lure in/weaken Steels so Salamence can clean up. It also takes up your Z move slot, which could be used on a more worthwhile mon like Volcarona, Lando-T, or Gyarados. Speaking of Gyarados, it's Salamence's main competition as a Moxie snowballer. Gyarados and Salamence I feel are definitely not on the same power level, but Gyarados is better. Gyarados' better defensive typing, Water STAB, bulk, and ability to break through Steels is valued a lot more than Salamence's perks such as a higher Speed stat. That higher Speed stat is kind of meaningless though, since every relevant Scarfer in the tier is faster than Base 100 Speed and can revenge +1 Salamence easily. Salamence's SPL record is also very...shaky. For a B+ mon it has only been brought 4 times as of the Semi Finals, and it has only one 2 of them. It's not a large sample size, but the fact that the sample size is that small to begin with should be an indicator that Salamence just isn't worth running that often. All in all, Salamence is a lot worse now, and having it in the same rank as Gyarados feels wrong. It makes more sense to drop Salamence than raise Gyarados, however, since Gyarados has some issues too, but Salamence's are imo much larger and exploitable.
B -> B-/C+: Yeah, Buzzwole isn't that great. It just...doesn't do enough to warrant its B ranking. I don't think it's worthless. I think a well played Buzzwole can be pretty annoying to deal with and can be decently effective, and it seems better than most of the C ranks, but Buzzwole is just...meh. It's been brought 3 times in SPL, and it has won a grand total of none of them. It has some positive traits like being able to handle Zygarde effectively, but its benefits are far outweighed by its cons. Talk of a Buzzwole drop has happened before and there isn't much else to say. If you look at the upper ranks, many Pokemon listed give Buzzwole a headache such as Mega Metagross, Tapu Lele, Greninja, Tapu Koko, Volcarona, etc. The meta is not in favor of it at all thanks to most of the top tier Pokemon murdering Buzzwole with ease, and B- or even C+ would be a better fit for it.
B -> C+: I completely support this nomination. Zydog is honestly really bad, it's been brought 3 times to SPL and only won one of them. It's bulk is non existent, it's ability is worthless, it's weak without a Choice Band. In fact, that's its only viable set, Choice Band...which is completely outclassed by its 50% counterpart. Having Zydog two entire ranks from Zygarde (in A+) seems fair. Zygarde outclasses it in every way except for its Speed (Which isn't even that amazing since Greninja, Dugtrio, and Tapu Koko all outspeed it). It isn't the worst Pokemon in the world and it can have success in OU, but it's extremely niche, and that's what C ranks are for.
B- -> C+?: This has got a question mark because I'm a bit confused as to what this mon does to warrant its B- ranking that it isn't grossly outclassed by. If it's a more specially defensive Calm Mind user, there's Tapu Lele, Keldeo, and Tapu Fini. If it's a fat Regenerator pivot, there's Tangrowth (side note: this thing's win rate increased by ~3% after the semi finals, so more food for thought for a rise), Toxapex, and Slowbro. I've personally never fought against this thing on the ladder, nor have I ever used it. It hasn't been brought to any SM OU match in SPL so it doesn't have any results from there either. Can someone rationalize it to me? I don't recall this being mentioned anywhere in the thread, and if it was I didn't see it. This mon just seems really outclassed to me, and a mon this outclassed shouldn't be listed in B-. If this really can't be rationalized to reasonably give an explanation for a B- ranking and not in the niche C ranks, then that should be an indication for a drop.
Also whatever happened to Thundurus-T? There was a lot of talk about a possible rise and a lot of support for it to at least get out of C and into C+, but it was never risen nor given an explanation as to why it didn't rise and discussion dropped. Could we get a statement about that if possible?