I've been trying out both Honchkrow and Nidoking,and have been having great results.
Nidoking has incredible coverage-and is in my opinion the very best special sweeper. Such immense power-I don't now what it doesn't 2HKO frankly. I've been running Ice Beam/Fire Blast/Focus Blast/Earth Power and it is incredibly good at smashing physical walls and luring out special walls for the rest of the team to set-up on.
Honchkrow hasn't got as much love from me as Nidoking, but is still very, very good if played properly. Moxie plus Sucker Punch/Brave Bird turns him into a terrifying threat-and now has the ability to take out rock and steel types as well. Obviously, Rhyperior is out of the question but Superpower gives perfect coverage I think with Sucker Punch and Brave Bird.
I've been using these two on a HO team-which is where Honchkrow really shines. It may have terrible defenses, but dual screens from Azelf/Bronzong/Xatu(I prefer Azelf, but the other two have their uses)allow him to survive a hit or two if need be.
If you wanted too, you could probably use them in a great offensive core. Not only does Nidoking smash around Rhyperior-89% to 1HKO the tank Rhyperior on the strategy dex-but Nidoking and Honchkrow have excellent typing synergy. Nidoking can switch into rock and fighting and electric moves for Honchkrow, while Honchkrow can switch into Earthquake's. Sure, there is a water weakness not covered by either, but a Roserade or Kingdra easily solves that problem.
I'm not using Xatu currently, but I have used him previously in the BW2 metagame. Xatu has better bulk than you'd think, but on a HO team Azelf works so much better due to better speed and Stealth Rock. He's a decent counter to Roserade-Spikes and Sleep Powder and Toxic Spikes are bounced back and Zatu resists grass-and makes a good U-turn user on dedicated VoltTurn teams. He can become setup bait though very quickly-especially against Substitute users like Scrafty, where Thunder Wave or Toxic is useless.