Interesting, really interesting ;). Theorymon time :D.
Wow, this is going to change the UU metagame completely. Alakazam and Rhyperior will rule the UU tier from this moment on I think. Never thought it would ever happen
Let's start with Rhyperior. Rhyperior will be powerfull, but nothing game breaking. Rhyperior was used in old BL (yeah, some people liked to play it like me or
Age of Kings :D) and it was proved as nothing game-breaking and still checked with good effect. And you don't need to use Scarfer or CB Azumarill to beat it 1on1.
CB Rhyperior can't OHKO for example Milotic and even with max speed he can't outspeed Max Def/Max HP versions dealing maximum 73-74% damage and I don't need to say that Surf easily OHKO back, especially when Sandstorm in UU is rare (Hippotas ? Not many people love to start battle 5 against 6). The same looks for Rock Polish. Rhyperior without crit can't beat Milotic anytime soon. I may call it almost-perfect counter. Or at least really good check.
Another good check is Tangrowth, which needs only to watch out on CB Megahorn, which 2OHKOes. Against Rock Polish versions it wins, as it can take one Megahorn and OHKO back with grass attack. Situations is really similar with Donphan (which only fears Aqua Tail) and Torterra (Torterra handles Rock Polish versions, only needs to watch out on CB Megahorn). Heck, even Claydol is solid check, but needs to watch out on Megahorn and with Max HP/Max Def it can handle one hit from Rock Polish Rhyperior. Poliwrath and Quagsire may also work most of times, only having some troubles with CB Earthquake, which is great set-up bait for all those flyers and levitators. Also Weezing is another reason, that Rhyperior won't have an easy life. Yeah, it's really good pokemon, but not much stronger then Rhydon, which was far from game breaking. Rhyperior has many checks and I didn't mention all of them.
Alakazam... another strong guy, but still without Substitute it has troubles with most priority attacks. Even if someone runs Substitute, Special Defensive Drapion/Skuntank, Spiritomb and Chansey handles it more then well enough. It has few less checks/counters then Rhyperior, but I can't see it being banned in future. Scarfers may easily abuse his horrible physical defence, with Drapion being best bet. But I think that UU Hyper Offense will love one set - Dual Screening lead with Encore, especially with Inner Focus to abuse. Yeah, I think I'll need to try Alakazam soon, as I think it's more dangerous opponent then Rhyperior.
Umbreon came back to tier, in which he works much better IMO. Also Umbreon has good enough bulk with some defensive investment to even handle Focus Blast from Alakazam and has reliable recovery in UU unlike Registeel.
I'm surprised that Nidoqueen quit UU - It's really good defensive pokemon, which has good typing and now with Roserade gone one of the best Toxic Spikers in UU tier. Heck, Super Fang is good bonus for her, as she doesn't have good attacking power. Rhyperior won't help her with being more popular, but I guess she'll be back sooner or later.
Aggron in UU - I'm really curious which stone behemoth will end up more popular - Aggron or Rhyperior, as they're used in really similar way. And Porygon2 in NU - good, at last some non-psychic Trick Room user, I wanted one to built NU Trick Room team ;).
Charizard and Magmortar - wow, even more attacking power in NU. It's kinda scary with all those attacking monsters.
I guess that's it - I like those changes and they will shake UU metagame a bit. But I need to say it again - nothing really game-breaking.
