Been playing a fair bit with a few mons while also getting a view how other mons function in this gen, I guess I'll start:
I'm gonna be honest, I don't know if it's because I have a scarfer above base 95, Melmetal and/or defensive Toad (which at least two of those are almost on every team anyways)... But I think DD Kyurem-B is overrated/underwhelming. I haven't yet to lose to one DD Kyurem-B, because either Melmetal tanks and OHKOS with Double Bash, Toxic it with Toad or just revenge kill with Scarf Dragapult (which I have using for Zeraora). Sure, maybe something like Toad dies or Melmetal takes like 44% from +1 Fusion Bolt, but I just find it easy to deal it with already meta components such as Scarfers or Toad. I could see it being insane stacked with the likes of Dracovish, but at the point you're making yourself weaker to things like Scarf Dragapult and Hydreigon which got better honestly through these additions. Also Icicle Spear is just too unreliable without Skill Link I feel and Power Herb Freeze Shock either gets knocked off somewhere or you get a kill and left with a shit move afterwards (same with Icium back in SM).
I think the real thunder lies with Mixed LO Freeze-Dry, which just breaks common cores without needing to setup. Should it be suspect tested? Yeah, probably I could see the argument that it requires you to have a base 95+ scarfer or things like Melmetal on your team to check it well. Should it be quick-banned though? I honestly don't think so but that could just be me.
This thing is as solid as I hoped it would be, it just hits so hard. Dugtrio is annoying to it if it's locked into anything besides Double Bash, but it's not as hindered as say Terrakion is to Dugtrio. It's great bulk and offensive power allows it to beat many top tier mons such as Corviknight, Clefable and Toxapex even if you're locked into Double Bash, cause more than likely you're gonna flinch it to death or near it. It's bulk allows it to take on threats such +1 Kyurem-B, Aegislash, physical Dragapult and Zeraora in times of need. I think it's low-key busted, but we'll have to see where the meta ends up.
This mon has almost zero defensive counter play through it's SD set, I'm gonna be honest, it might be ban worthy if Dugtrio goes. Even without Shed Shell, I've been finding success through the SD Life Orb Edge/CC/EQ set, it just hits so hard. Defensive Toad only needs like 30% chip and it dies to +2 CC, and considering how much Toad needs to check that doesn't seem too hard. It's obviously revenge kill able much Kyurem-B, but unlike Kyurem-B I think that defensive counter-play just isn't there. I suspect a Phys Def Hippo resurgence in the future.
And thus, Toxic was bestowed and it's just as annoying/busted as it used to be. SubToxic is just gross as it allows it to break it's counter-play via Mandibuzz, Toad (physical sets), Umbreon etc. Corviknight does Pressure stall it though, so there's that I guess. I might need to be looked at in the future.
Hydreigon with the access of Roost is big threat, I could see it being one the best mons in the tier due to it having longevity now. I also found Scarf is even better now considering the importance of breaking +1 base 95 now. Overall, really good Pokemon, probably one of the best in OU.
This thing getting Toxic is a huge boon in breaking down Pokemon like Seismitoad as well putting Dragapult on a faster time than Wisp does. It also one of the few Pokemon that reliably checks Melmetal so I could see a Pain Split set in the future.
Venusaur is great! Great sun abuser which has been missing (with the exception of probably Roserade) especially with base 100 fire type moves in Weather Ball, which is now legal with Growth? I'm pretty sure it wasn't before. I could see Sun being a very strong arche-type or mix sun-sand teams. Kommo-o is obviously the best check to it right now, and that mon has been on the up as of lately but I feel like that won't hinder the success Venusaur will find in the tier.
Blastoise is actually really solid as Shell Smash user, though Cloyster is better in most cases. Situations where Toxapex are not on a team is where this Pokemon truly shines, I've seen SS Spout/Surf/Aura which does a absurd amount of damage if you force the switch with SS. It will probably drop to UU, but probably be banned to BL in the later future via suspect is my guess.
This mon is a lot better than I expected, but I guess that's to be expected when Gliscor, Tangrowth and Lando-T aren't in the tier. It breaks common Electric-immunities such as Seismitoad, Gastrodon etc. via Grass Knot which also does a lot to Hippo unless it's heavily SpDef invested. PFists/Play Rough/CC/Grass Knot or Volt Switch with Expert Belt/Life Orb seems to be it's best set, and I find it very hard to deal with defensively due to that insane coverage. Best bet of dealing with this? Trap it with Sash Dug or run Scarf Draga, because this thing is insane.
I personally haven't used it, but, SubRoost and Choice Specs seems SUPER good in this meta where common Water-types are 4x weak to Freeze-Dry. I think this will be one of the best mons in the tier, due to it beating almost every defensive core in the game. Also this thing just 6-0s stall with SubRoost, so if you see on the enemy when you're running stall, just forfeit lol.
Oh SPEAKING of overrated, I found this mon to be ass. Maybe because I haven't fought it in rain? But via all the Fairy types running Sp.Def to beat Hydreigon and Dragapult, Dragapult and Gengar just being so good, water-immunites, Toxapex etc. I find it to be very bad. Maybe stacked with Vish it will be good? But then again, Mantine Rain stacked with Vish also good so what's to say about how good this mon is? Imo use this as a Scarfer to deal with Kyurem-B if you want to use it.