Lucario@ Quick Claw.
Trait: Inner Focus/Steadfast doesn't really matter which.
1: Aura Sphere.
2: Close Combat.
3: Swords Dance.
4: Ice Punch
Lucario is a all around fighter with a variety of specials and physicals. Swords dance is for boosting his already pretty good attack. Aura sphere never misses plus it does some decent damage. Close Combat does extreme damage and with a couple of sword dances it can knock out a lot of things. Ice punch is maily for dealing with annoying dragon types.
Trait: Rough Skin (If you can get it.)
1: Dragon Pulse.
2: Dragon Rush.
4: Draco Meteor.
Garchomp is amazing. His offense and defense are ridiculously high and his moves are powerful. Earthquake will take out fire, poison, steel, and electric. Dragon Pulse and Rush are his STAB moves and Draco Meteor will finish off any survivors.
Trait: Hydration (Again, if you can get it.)
Nature: Lax. (To improve on the Defense.)
3: Rain Dance.
Swanna is a good flyer and surfer. Plus, it is just plain cool. Fly and Surf are not only good moves, they can transport you around outside of battle. Rain Dance will boost Surf and activate Hydration ability. Hurricane is just a filler, but it's a good flying move.
Magmortor: (Note, only in Black 2.)
Trait: Flame Body.
1: Fire Blast.
2: Lava Plume.
3: Confuse Ray.
Magmortor is strong with his Special Attacks. Fire Blast is a powerful move, but it has low accuracy. Lava Plume has decent power, the bad part is it hits your teammates in a double/triple battle. Confuse Ray is filler but can be helpful. Thunderbolt gets rid of the water type threat.
Nature: Lax. (Again with the bad defense.)
I personally like Ditto in dragon battles. He turns into one and bang, Ditto super effects him. Ditto is really good against Iris or in Drayden's gym.
Trait: Clear Body
Nature: Timid. (It needs more speed.)
1: Meteor Mash.
2: Hammer Arm.
3: Zen Headbutt.
Metagross has awesome defense. Meteor Mash does decent damage and is the STAB for this Pokemon. Hammer Arm does major damage and should only be used after a few uses of Agility. Zen Headbutt is another STAB move and is pretty powerful. Agility is to raise Metagross's horrible speed stat.