The Lead:
Moltres @ Choice Scarf
Pressure
Timid
252 Sp.Atk 252 Spe 6 HP
Fire Blast
Air Slash
Hidden Power (Grass)
U-Turn
Basic CS Moltres lead. Dishes out tons of damage with STAB Fire Blast, covers bulky waters with HP Grass, U-Turns out of threats into something more useful. Not really much to be said here, it's one of the most popular leads in UU for a reason.
Mesprit @ Leftovers
Levitate
Timid
252 HP 92 SpA 164 Spe
Stealth Rock
Thunder Wave
Thunderbolt
Psychic
Paralysis and stealth rock support are what made me choose the supporting attacker mesprit set. Originally it was the choice scarf lead in place of moltres, but I found this to be far more effective. Come in on a fighting type or a choiced ground attack and start setting up (usually be twaving the switch) then setting up rocks. Tbolt to hit fliers and bulky waters and Psychic for a powerful STAB.
Milotic @ Leftovers
Marvel Scale
Calm
252 HP 200 Def 56 Sp.Def
Surf
Ice Beam
Rest
Sleeptalk
My sleep absorber, mixed wall/bulky water, and general counter to most special attackers. The EVs allow me to not be 3HKOd by Moltres' HP Grass, while being able to loop rest and sleeptalk to eventually KO it with surf/ice beams. I really like having a status absorber on my team because having one of my sweepers crippled isn't very fun. lol
Leafeon @ Leftovers
Leaf Guard
Jolly
132 HP 160 Atk 216 Spe
Leaf Blade
Swords Dance
Wish
Baton Pass
Leafeon makes an amazing support pokemon. With great speed and physical bulk leafeon can easily set up a +2 atk baton pass and still be able to come back later to do something. Leafeon also reaches an impressive 592 Atk after a swords dance boost and can seriously dent a lot of things with it's stab leaf blade, ridding me easily of a lot of bulky waters/grounds. Wish support, is always a nice thing to have, and like most of the other eeveelutions, it finds a place on his set as well. I opted for it over grasswhistle/roar/synthesis because I don't like grass whistle's 55% accuracy, haven't found leafeon being the target of phazing (since I try and bring it out a little later into the game if I can), and really wanted it to be more of a team player so after I pass its swords dance boost I could more easily ensure whatever I passed into survived with a bit more manageable HP.
Aggron @ Life Orb
Rock Head
Jolly
252 Atk 252 Spe 6 Def
Head Smash
Aqua Tail
Low Kick
Rock Polish
Rock Polish Aggron is one of my all time favorite pokemon. STAB Head Smash without fearing too much recoil damage off of 319 atk (with life orb) and coming from a poke with 436 speed (after a rock polish) is a HUGE threat to pretty much anything, including a lot of physical walls. Basically the only thing that can take this thing down is something with a fighting type priority move such as vacuum wave, which will just about always ohko me ; ; But that aside, aggron is a fantastic late game sweeper, and usually the last pokemon I reveal. But should he get a pass from Leafeon, beware the almost inevitable sweep.
Ambipom @ Life Orb
Technician
Jolly
252 Atk 252 Spe 6 HP
Fake Out
Double Hit
Payback
U-Turn/Low Kick
Ambipom is easily one of the best physical revenge killers in UU. Stab Technician Fake Out gives you usually a pretty huge amount of free damage on most pokemon. Double Hit can also seriously dent quite a lot of things, as well as the other two attacks. I haven't fully decided weather to go with U-Turn or Low Kick. U-Turn allows for some really nice Moltres synergy, but Low Kick does better allow me to KO things like Aggron.