Lead-Nite
Dragonite @ Expert Belt
Ability: Inner Focus
EV's: 144 HP/24 ATK/128 SpA/20 SpD/192Spe
Nature: Mild (+Sp. Atk, - Def)
~ Fire Blast
~ Earthquake
~ Hidden Power [Grass]/Ice Beam
~ Superpower/Draco Meteor/Outrage
Fire Blast allows Dragonite to 2HKO Occa Metagross and 92 SpD/Sassy Bronzong, factoring in Leftovers recovery. Earthquake can be used to KO Heatran as well as Infernape. Hidden Power easily 2HKO's Swampert, while Ice Beam scores the old one-two on Hippowdon, depending on which bulky ground you want to counter.
The last move is up to you. Superpower OHKO's both Tyranitar and Ambipom, while Draco Meteor gives Dragonite a powerful 140 powered STAB. Outrage is also a viable option if you want to go with a bang.
Dragonite's EV's allow you to always survive survive a Meteor Mash and Bullet Punch from Metagross, 2 Gyro Balls from Bronzong, and an HP Ice from Timid Heatran, assuming no prior damage (and there should be none, since this Dragonite is meant to be used as a lead). Hippowdon will also never 2HKO you with either Stone Edge or Ice Fang. Finally, 192 Speed EV's always outspeeds + natured Tyranitar.
Fire Blast vs. LeadGross (252/0)
77.74% - 91.21 % (2HKO with Occa)
Fire Blast vs. Bronzong (252/92)
56.80% - 66.57%
Ice Beam vs. Hippowdon (252/72)
57.14% - 67.14%
HP Grass vs. Swampert (252/0)
82.43% - 97.01% (Note that HP Grass and max Sp. Atk will never OHKO Swampert with Expert Belt)