Damn these are some major changes!
Zard Y - While I know this is technically BL because it was banned in UU Beta, I feel like UU is in a state that maybe Zard Y can receive a re-test. Latias is one of the best switch-ins, even back in ORAS/XY, Sp.Def Hippow can switch in but is pressured somewhat, Sap Sipper Trapper Azu also can switch-in. Faster pokemon like Cobalion, Terrakion, Raikou, Mega Manetric, Infernape etc. all threaten it/revenge kill it. It still would stand that Zard-Y would be one of the best, if not the best Mega if it was reintroduced. Only time will tell.
Not gonna bother talking about Mana/Nite, neither of these two have a chance of being reintroduced due to Veil being back at full force with Alola-Ninetales.
- (OU to UU) This mon seems interesting, it being back in UU could mean the return of Semi-Rain teams with support to beat Primarina. I think this mon also has good potential with DD or Focus Energy + Agility in Veil.
- (OU to UU) This mon is busted, while it wasn't so great in OU, this thing literally nuked everything that wasn't Skarmory. While UU may have Mega Aggron, that's it in terms of switch-ins. A Mega. Also Trick Room looks super abusable with mons like Alola-Wak and Crawdaunt in the tier. This thing is gonna start a surge of Semi-TR and Full Trick Room teams. Wouldn't be surprised if it was banned.
- (OU to UU) This finally happened, a nail in the coffin to VoltTurn (with losing Rotom-W as well) and a blessing to Trick Room. Single handily walls Mega Manetrics STAB and Coverage and smacks everything super hard. I could see this being a A+ mon.
- (OU to UU) Finally! I've been waiting to use this mon in this tier! Lycanroc-Dusk has great speed, solid attack and a really good ability which makes Drill Run stronger than EQ. It's ability makes its Rock-priority move slightly stronger (Accelerock) which is also nice. SD Lycanium-Z is super scary, so much I could mons like Hippowdon and Krookodile rising in usage (also that Rotom-Wash is gone also helps these mons). Fire Fang can nab kills on Scizor if they try to switch-in, unfortunately it doesn't get Ice Fang for Gliscor but SD Stone Edge should hurt.
- (OU to UU) It's back. Aurorus/Sandlash Veil is now dead now that this thing is back, while Hawlucha didn't return with it (which is good cause that thing is busted in OU lol) with mons like Kommo-o etc. in the tier, Veil got a lot better.
- (OU to UU) It's finally back! A strong and fast ghost type that also threatens the multitude of Fairy-Types in the tier. The lack of Bisharp and Weavile is this tier makes this mon scarier than the last time it was was here, but we have the amazing Pursuit Trapper in Alola-Muk which walls this thing, though Destiny Bond paired with a mon like Latias can be scary if your only answer to those two is Muk.
- (UU to OU) Oof. This is huge for UU. Losing one the best VoltTurn staples and Gliscor answer. It was bound to happen, and I feel eventually Gliscor will follow (idk if ban or usage). Pokemon like Swampert, Crobat and Scizor etc. also get better with Rotom rising. The tier is gonna change a lot due to this.
- (NU to UU) Poor toad. The whole reason he rised up was because of Rotom-W lol.
- (RU to UU) This is big for RU, losing the best offensive SR setter and one of the best sweepers. This thing was S rank in RU, that's how good it was.
- (UU to RU) Oh how the mighty have fallen, Mega Blastoise has finally dropped. This thing is going to be good, probably the best Rapid Spinner as it beats every hazard setter (except probably Chesnaught) in the tier. Hits super hard, has good coverage, good bulk. I could see this being S rank material honestly.
- (UU to RU) New defogger for the tier, Mandi is probably the best answer to Doublade now. Though it is fat, a lot of the offensive rockers threaten it like Nidoqueen, Gigalith and Rhyperior. It does beat Chesnaught though, which is nice.
- (NU to RU) NU loses one it's best scarfer, specs user, VoltTurn staple and defogger. I'm not sure how I feel about it in RU, with mons like Nidoqueen, Mega Abomasnow, Salazzle, Durant etc. in the tier.