Haven't really been involved in UU Alpha, but I've played a bit of Beta and been following the threads and I'm surprised no one has really been talking about Keldeo.
Keldeo-Resolute @ Choice Scarf
Ability: Justified
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Hydro Pump
- Secret Sword
- Scald
- Icy Wind
From what I've seen, heard, and experienced, it's extremely threatening. Its Choice Scarf set is probably the best right now, but Choice Specs, Calm Mind + 3 attacks, and Substitute + Calm Mind are all very strong as well. Choice Scarf gives it enough speed to outspeed threats such as +1 Dragonite, +1 Salamence, Weavile, Mega Aerodactyl, Zygarde-10%, Gengar, Raikou, and Serperior, in order to either revenge kill them or slow them down with Icy Wind so that something else can finish them off, and its natural power allows it to still hit hard against the offensive teams that make up most of the meta right now. Choice Specs provides a lot of immediate power and the Calm Mind sets destroy bulky teams. Its typing also offers cool defensive benefits, such as allowing it to check dangerous Pokemon like Weavile, Scizor, Bisharp, and Kabutops. Keldeo is versatile and easy to fit on teams, but it does have some drawbacks. A lot of common Pokemon in UU resist its STABs (like Latias, Dragonite, Azumarill, Salamence, Primarina, Tentacruel, Starmie, and Slowbro). That said, a smart player can take advantage of many of the tier's Keldeo answers, and Choice Scarf Keldeo in particular benefits heavily from Pursuit support.
Primarina @ Choice Specs
Ability: Torrent
EVs: 4 Def / 252 SpA / 252 Spe
Modest Nature
IVs: 0 Atk
- Hydro Pump
- Moonblast
- Scald
- Psychic
Primarina is another specially offensive Water-type with typing that allows it to serve as an offensive answer to many prominent threats. It's a lot slower than Keldeo, but its offensive typing makes it harder to wall and its special bulk is better. It offers a lot of value to a team because it can check Dragon-types, Weavile, and Keldeo while also pressuring slower Pokemon and anything it can survive a hit from. Primarina is held back a bit by its mediocre speed tier, which leaves it outsped by Pokemon like Breloom and Bisharp.
Sacri' also mentioned a defensive set in the Alpha thread
here. I haven't had the chance to test it out myself yet, but it looks like it could have potential.
Salamence @ Flyinium Z
Ability: Moxie
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Dragon Dance
- Dragon Claw/Outrage
- Fly
- Earthquake
Salamence was something I used extensively while it was still ORAS legal, and this is basically a better version of the old Moxie Dragon Dance set. Z-Fly lets it get past a lot of checks and counters that stop it otherwise (not needing to hit Fairy-types with Iron Tail and run the risk of missing is really useful, as is the ability to beat bulky stuff like Suicune, Swampert, and whatever else without locking itself into Outrage). Salamence has the bulk, typing, and immediate threat to find a lot of setup opportunities and rolls through teams as soon as it finds the right moment. I've been testing Outrage over Dragon Claw to see if the immediate power is worth the cost of being locked into the move, since Dragon Claw is really weak without a boost and sometimes I just want Salamence to smash something right off the bat. The testing has been inconclusive so far, since Salamence has usually gotten its opportunities to set up when the opposing team is weakened enough that the Dragon-type STAB move I chose didn't matter. I haven't had the chance to try offensive or defensive Defog sets or Choice Band, mixed attacking sets, or Dragon Dance sets without a Z-move, but this seems like the best Salamence set in this meta by far.
In other news, Porygon-Z, Mega Slowbro, and Azumarill are all broken.
Edit: Sacri' has informed me that Dragonite and Salamence are also broken. I agree that Dragonite is busted. I'm not sure if Salamence is borderline broken or actually broken and just overshadowed by stuff that's even worse so that it seems semi-balanced.