I currently started UUing quite a bit, and this is how i've seen how the new UU threats have done:
Raikou
Sub Calm Mind: Walled impeccably by Venusaur, if it doesn't run HP Ice, and Steelix if it does. Registeel handles it handily, though it doesn't like boosted Thunderbolts. Dugtrio obviously rapes it. Most priority moves hurt it a lot, though Sucker Punch is set-up bait. I've been using Azumarill, and Aqua Jet does usually about 40% to it after Raikou sets up and nets a kill.
Specs: Only seen a couple, though it's basically read above, but predicting around it easier.
Froslass
Spiker Lead: Gets down Spikes pretty well, had a few mind-wars with Taunt and Destiny Bond. After that, it's basically dead weight. Anything that resists Ice Beam or has above-average Special Defense handles it usually pretty well. Registeel, Azumarill, and anything with priority keep it in check.
Offensive Anti-Lead: Pretty annoying. Usually kill your lead then send in a counter and it runs. Azumarill fears Thunderbolt, but Aqua Jet outspeeds and deals >75%. Registeel handles it easily.
Rhyperior
Choice Band: Prediction keeps this in check. Azumarill handles this thing brilliantly with it's natural bulk and Waterfall under it's wing. Most bulky waters do a great job. Stone Edge is set up bait for Grounds/Steels/Rocks, while Earthquake is set up bait for Mismagius and other Fliers/levitators.
Rock Polish: Can be quite a handful. Azumarill has natural bulk and Waterfall and Aqua Jet so Azumarill is quite handy there. Bulky waters, again. Probably the most devastating of the new threats, IMO.
Lead / Wall / Support: Bulky, but 2 super effective hits and it's gone. It'll lay down Stealth Rocks, then maybe send off a hit and it's usually dead. Azumarill, again, keeps this in check. Bulky waters in general, really.
Alakazam
Specs: Prediction once again overcomes this. Registeel walls it, and Sucker Punch and almost any priority move fucks it over. Spiritomb rapes it too. Not very threatening IMO.
Calm Mind: Can be devastating, but again, Sucker Punch and priority keep this at bay. Spiritomb walls it almost completely.
Sub/Encore + Set Up: Alakazams most annoying and devastating set IMO. If played right, it can sweep through most teams. However, Spiritomb walls it basically 100%.
Gallade
Swords Dance: Personally, I believe it's overrated. Azumarill keeps it in check nicely. Spiritomb also walls it pretty well. Priority and Sucker Punch are all over it, really.
Scarf: Can run through weakened teams, but again, most pokes can. Prediction fucks it over. Again, priority and Sucker Punch go a long way.
Umbreon
Wish Pass: Gallade. Need I say more?
Curse Pass: Gallade again rapes this. =/
Probably not the most accurate of opinions, but their mine not yours. Overall, i'd say the new threats are:
Raikou: UU/BL
Froslass: UU
Rhyperior: UU/BL
Alakazam: UU
Gallade: BL
Umbreon: UU