I'm kind of new to the world of UU, and this is my first team. The synergy here comes from entry hazards and racking up damage with them. I have used this team, and it nearly never fails me. I decided to post here as a way to get second opinions about my team and strategy.
Roserade(F) @Black Sludge
Timid Nature ~ Natural Cure
200 hp/120 def/52 spdef/136 spe
~Spikes
~Giga Drain
~HP Fire
~Toxic Spikes
Roserade is my main lead. I send her out to set up as many entry hazards as possible and run. She, like all Grass types, has many weaknesses, so I remedy this by switching out into another pokemon who resists that attack. She's the crux of the team, so it's important that I keep her alive.
Swampert(M) @Leftovers
Adamant Nature ~ Torrent
/6 atk/125 def/125 spdef/252 spe
~Earthquake
~Waterfall
~Stealth Rock
~Roar
This is where some of my strategy comes in. After Roserade sets up some Spikes, I switch to Swamp, stealth rock, and Roar away. This racks up damage, poisons, and breaks focus sashes and sturdies. I have defense EVs to that I can keep him alive and speed to sort of even out the -1 priority of roar.
Xatu(M) @Leftovers
Calm Nature ~ Magic Bounce
252 hp/240 spdef/16 spe
~Thunder Wave
~U-Turn
~Roost
~Psychic
Xatu is my backup for Roserade. Nearly all teams have a hazard setter, and Xatu can use this against them. Because of Magic Bounce alone, he can switch into nearly any attack and counter it. U-Turn really helps me, as he can get out of trouble in a jam and break sashes and sturdy. As long as Xatu is still in, I can't be touched by status moves.
Honchkrow(M) @Life Orb
Adamant Nature ~ Moxie
252 atk/4 def/252 spe
~Sucker Punch
~Superpower
~Brave Bird
~Roost
After I've softened up the enemy a bit with my entry hazards, Honckrow, Empoleon, and Heracross come in and sweep. Honckrow's insane attack power combined with a Life Orb will kill nearly anything he attacks. I am considering switching out SP for Night Slash in the near future.
Empoleon(M) @Petaya Berry
Modest Nature ~ Torrent
252 spatk/4 spdef/252 spe
~Agility
~Substitute
~Surf
~Ice Beam
Ah, the SubPetaya strategy. For those who don't know, here's how this works. If something faster than me comes in, I set up a substitute. The next turn, I use agility while the enemy's breaking the Sub. I repeat this until the Petaya berry kicks in, where I get a spatk boost. This makes Empoleon an unstoppable special sweeper.
Cofagrigus(M) @Leftovers
Bold Nature ~ Mummy
248 hp/ 8 def/252 spdef
~Shadow Ball
~Will-O-Wisp
~Pain Split
~Haze
Taking suggestions from PTJon7, the spinblocker/wall. Since I focus on hazard damage, it's important to have a spinblocker, and I had been thinking of replacing Heracross anyways. He can stop hitmontop and blastoise from getting rid of my work, and can wall nearly anything. I gave him higher spdef so his walling capabilities wouldn't just be defense.
Well, that's my team! Leave any comments or suggestions you have. I'm always up for criticism, especially since I'm still kind of new to UU.

Roserade(F) @Black Sludge
Timid Nature ~ Natural Cure
200 hp/120 def/52 spdef/136 spe
~Spikes
~Giga Drain
~HP Fire
~Toxic Spikes
Roserade is my main lead. I send her out to set up as many entry hazards as possible and run. She, like all Grass types, has many weaknesses, so I remedy this by switching out into another pokemon who resists that attack. She's the crux of the team, so it's important that I keep her alive.

Swampert(M) @Leftovers
Adamant Nature ~ Torrent
/6 atk/125 def/125 spdef/252 spe
~Earthquake
~Waterfall
~Stealth Rock
~Roar
This is where some of my strategy comes in. After Roserade sets up some Spikes, I switch to Swamp, stealth rock, and Roar away. This racks up damage, poisons, and breaks focus sashes and sturdies. I have defense EVs to that I can keep him alive and speed to sort of even out the -1 priority of roar.

Xatu(M) @Leftovers
Calm Nature ~ Magic Bounce
252 hp/240 spdef/16 spe
~Thunder Wave
~U-Turn
~Roost
~Psychic
Xatu is my backup for Roserade. Nearly all teams have a hazard setter, and Xatu can use this against them. Because of Magic Bounce alone, he can switch into nearly any attack and counter it. U-Turn really helps me, as he can get out of trouble in a jam and break sashes and sturdy. As long as Xatu is still in, I can't be touched by status moves.

Honchkrow(M) @Life Orb
Adamant Nature ~ Moxie
252 atk/4 def/252 spe
~Sucker Punch
~Superpower
~Brave Bird
~Roost
After I've softened up the enemy a bit with my entry hazards, Honckrow, Empoleon, and Heracross come in and sweep. Honckrow's insane attack power combined with a Life Orb will kill nearly anything he attacks. I am considering switching out SP for Night Slash in the near future.

Empoleon(M) @Petaya Berry
Modest Nature ~ Torrent
252 spatk/4 spdef/252 spe
~Agility
~Substitute
~Surf
~Ice Beam
Ah, the SubPetaya strategy. For those who don't know, here's how this works. If something faster than me comes in, I set up a substitute. The next turn, I use agility while the enemy's breaking the Sub. I repeat this until the Petaya berry kicks in, where I get a spatk boost. This makes Empoleon an unstoppable special sweeper.

Cofagrigus(M) @Leftovers
Bold Nature ~ Mummy
248 hp/ 8 def/252 spdef
~Shadow Ball
~Will-O-Wisp
~Pain Split
~Haze
Taking suggestions from PTJon7, the spinblocker/wall. Since I focus on hazard damage, it's important to have a spinblocker, and I had been thinking of replacing Heracross anyways. He can stop hitmontop and blastoise from getting rid of my work, and can wall nearly anything. I gave him higher spdef so his walling capabilities wouldn't just be defense.
Well, that's my team! Leave any comments or suggestions you have. I'm always up for criticism, especially since I'm still kind of new to UU.