So there are a LOT of noms that have been made in the past couple weeks, and since they're all things that seem susceptible to happening, here are my personal opinions on them (they'll be short due to how many noms I'm mentioning).
Cresselia to A: Agree Any team that's bug, dark, or ghost type attacks are on a pokemon thats already fainted is going to have serious trouble against Cress. It's a great calm mind sweeper and can also effectively support a team with dual screens for setup sweepers and lunar dance for any of its unhealthy teammates. Unpredictable, and able to fit onto many play styles with ease.
Sneasel to C-: On the fence Not too many people have talked about this nom, but Sneasel does possess a niche as a fast pursuit trapper and dangerous sweeper with a free turn. Just don't know HOW effective it is in doing these things since I never see it.
Durant to C-: Agree While its abysmal bulk and the low accuracy provided by hustle hinder it, the short time it's out on the battlefield can be used to plow through unprepared offense teams and even some of the tier's bulkiest mons (as shown by calcs done a few pages ago). This thing can definitely be an asset to teams with unprepared opponents.
Donphan to C/C-: Agree Offensively outclassed by Krookodile, Swampert, and Mamoswine, and outclassed as a spinner AND setter by Forretress, and again as a spinner by Tentacruel. I could go further into detail, but I've already specifically posted about this thing, so just look at that post for my full explanation.
Mega Shark to A-: On the fence It definitely can be deadly late game, but its bulk, priority moves in espeed and mach punch, and new and prevalent checks in Conk and Sylv keep it from being as effective as it once was. Still great, however.
Florges to A- or B+: Agree Sylveon outclasses this thing both offensively and as a team cleric, and this shouldn't be new info at this point. It has synthesis and calm mind to differentiate itself a bit, but is reliant on quite a few CM boosts to do much damage.
Dragalge to B-: Disagree Still a very reliable switch in to fighting type moves, scald, and fire type moves and as many others have said, the only dragon capable of reliably KOing fairies on the switch. Still on par with many B mons.
Aromatisse to C+ or C: Agree Another pokemon that is hopelessly outclassed in its respective roles by Sylveon, but even more than Florges, sure its immune to taunt, but what can it do offensively alongside supporting its team? Nothing that Sylv and Florges can't do better.
Porygon2 to B+: Disagree Bsu gave a pretty good explanation as to why B rank is justified, so ya.
Mega Houndoom to B: Disagree The meta game isn't totally favorable to this thing in some ways, but in others, such as the prevalence of threats that it can check VERY well and/or set up on, it is. Definitely not worth the drop considering the popularity of Celebi and its impressive sweeping capabilities.
Toxicroak to A: Disagree Without setting up, it isn't able to sweep, and even when it has an NP or SD under its belt, it's average speed and not so good bulk leaves it susceptible to being revenge killed with ease by things like Krookodile and Infernape. It's a very good pokemon, but not on par with those in A.
Welp, that took a LONG time, but I hope that what i said picks up some more discussion on the pokes that everyone hasn't given much attention to.