A nomination or two, do not want to comment much on other players' nominations, they are very good in my opinion.

(A-) -> (A)
Over the past couple weeks the metagame has grown, for lack of a better word, increasingly violent. Heatran, Weavile, Melmetal, Dragapult, Garchomp, Kartana, Tapu Lele, Urshifu, Zapdos and even offensive Landorus all hit like freight trains while doing an increasingly insufficient job soft-checking each other; Zapdos 2hko's Garchomp with Hurricane, Choice Band Weavile 2hko's Heatran, Melmetal 2hko's Landorus through Intimidate.
Match-ups between offensive teams are starting to resemble bloodbaths between two gangs of berserkers where the side that gets in more hits comes out on top, and Dragonite is one of the few Pokémon that can keep up with the carnage; being both a water and a fire resist with reliable recovery that can fit on offensive teams is a great niche, since Dragapult and Garchomp lack Roost, and Multiscale grants it very good bulk, making it a reliable check to

,

,

,

,

and even the rising

.
It has also proven that soft-checking it with Will'o'wisp may not be enough to prevent it from sweeping. I imagine it can also successfully run utility sets with Heal Bell, Thunder Wave, Toxic or Defog, a specially offensive one with STAB Hurricane, or maybe even a hyper-offensive set:
Dragonite @ Normal Gem *
Ability: Inner Focus **
EVs: 8 HP / 252 Atk / 248 Spe
Adamant Nature
- Dragon Dance
- Dual Wingbeat
- Earthquake
- Extreme Speed ***
Something like this?
* +1 252+ Atk Normal Gem Dragonite Extreme Speed vs. 0 HP / 0 Def Tapu Lele: 242-285 (86.1 - 101.4%) -- 87.5% chance to OHKO after Stealth Rock
** Everybody assumes Multiscale anyway, so one can try to capitalize on the Landorus switch-in
*** Psychic terrain only obstructs priority moves by grounded Pokémon

(B) -> lower
This is in my humble opinion the Pokémon that suffered the most the couple months. It had a very unreliable - read: match-up fishy - typing both offensively and defensively to begin with, what with nearly 100% of the tier's teams running both a ground and a steel type, but the recent diversification of ground types, with players starting to explore Garchomp, Gastrodon, Hippowdon, Seismitoad and Excadrill more instead of the standard Landorus. Melmetal's rise to dominance similarly hurts it, as Nihilego is incapable of fitting enough coverage to threaten all of its checks, and two Pokémon notably beat it no matter what offensive set it runs,

and

.
Some teams have managed to utilize it successfully as a fast Toxic Spikes setter, but YMMV on how reliable this is.

(A+) -> keep (A+)
Maybe a week or two ago I would have supported a rise to S-, but currently the metagame is getting too aggressive for it. Offense is in my humble opinion definitely the best way to currently play the tier, and
when it gets stuck in match-ups where nearly every opposing Pokémon can 2hko it, it gets quickly reduced to cannon fodder, getting maybe 2 free turns.
Edit: Melmetal's rise is also bad for Clefable.