This is one of my favorite cores to use right now in UU:
Bisharp @ Leftovers
128 HP, 252 Atk, 128 Speed
Adamant Nature (+Atk, -SpA)
Zapdos @ Life Orb
180 HP, 252 SpA, 76 Spe
Modest nature (+Spa, -Atk)
-Hidden Power Ice
Bisharp and Zapdos don't have great synergy by type, but they can use their unique movesets to break walls pretty well, and then have Zapdos or another sweeper clean up afterwards. Bisharp's goal is to come in on the things it walls and set up a Sub or an SD. Roserade, Crobat, and Umbreon are good Pokemon to set up on, though if the opponent is locked into a Choiced attack that Bisharp can deal with, that's even better. Scarf Flygon's Outrage is a great move to come in on, as you can potentially set up a Sub AND an SD if you get some confusion hax. Otherwise, you'll probably have to settle for only a Swords Dance.
Bisharp can then wreak all sorts of havoc on the opponent's team provided that the Bulky Waters are out of the way. A +2 Sucker Punch does loads of damage to the Waters, but all too often the Water will try to Phaze you. I'm looking at you, Blastoise. Fire types are usually OHKO'd by Sucker Punch, and those that try to do some clever switching to get away from Sucker Punch will have to take Iron Head, which has the same Base Power as the fearsome Sucker Punch.
Zapdos makes for an excellent cleaner since he can finally run Modest Life Orb without being taken down by faster opponents thanks to Agility. The only drawback to Agility Zapdos is that BoltPowerIce just isn't a great combo in UU unless you have the hazards/attackers to soften up the opponent's team a bit. If you can wear down the opponent than Zapdos' Speed boost makes it a force to be reckoned with since all those Scarfers that enjoy revenge killing Zapdos suddenly find themselves outspeed and KO'd.
Threats to this core include
Swampert walls this core, so it's important to have Grass-type coverage on your team. Roserade is a nice choice, though some of the more unruly Swamperts will either use Subsitute or a Choice Banded Earthquake to get rid of Roserade. If Roserade is too frail for your liking, then try Shaymin, who walls Swampert consummately and SEED FLARE.
You need a hazard setter, as this core is pretty useless without a couple hazards on the opponent's side. Nidoking makes a great Stealth Rocker since it keeps up the offense from the core, but doesn't do a whole lot for type synergy. Swampert's lone weakness is covered by both Zapdos and Bisharp, and Bisharp's Fire weakness is handled well by Swampert.