OU+ Team [RMT]
This team is very defensive. The sweepers have defensive EV's, but can hit hard after a boost. I tried to create a team that can simultaneously receive several attacks and strike hard. In my team, in addition to special / physical sweeper and special / physical wall, there is always a annoyer, a cleric and a Phazer to face the most threats.
I try not to repeat any weakness.
Lead / Physicall Wall / Phazer:
EV's: 252 HP / 252 Def / 4 Atk
Nature: Relaxed
~ Waterfall
~ Earthquake
~ Roar
~ Ice Beam
The first turn it makes Stealth Rock.
EQ as main attack and Ice Beam for Salamence mainly.
With Roar is the team Phazer and prevents the rival to increase its stats.
Special Sweeper:
Latias @ Life Orb / Leftovers
EV's: 128 HP / 128 SpA / 252 Spe
Nature: Timid
~ Surf
~ Dragon Pulse
~ Calm Mind
~ Recover
I use her as special sweeper, but I give her the EV's of the defensive set for best durability and after one Calm Mind she can do much damage anyway.
Surf and Dragon Pulse can hit at least neutral to all except Pokemon Empoleon.
Calm Mind to boost your SpD and your SpA and Recover to recover from the damage they'll shift in using Calm Mind.
Physical Sweeper:
Gyarados @ Leftovers
EV's: 156 HP / 108 Atk / 100 Def / 144 Spe
Nature: Adamant
~ Dragon Dance
~ Waterfall
~ Stone Edge
~ Taunt
I test this set and the offensive Gyarados and I obtain best results with this set.
Dragon Dance to boost its Attack and Speed.
Taunt to prevent a Phazer spoil the Dragon Dance boosts and stop the rival's walls.
As main attack Waterfall with STAB and Stone Edge for other Gyarados, Salamence and bulky waters.
Special Wall / Cleric
Blissey @ Leftovers
EV's: 252 Def / 40 SpA / 216 SpD
Nature: Calm
~ Thunder Wave
~ Flamethrower
~ Aromatherapy
~ Softboiled
She protects her teammates for status and special attacks. She is essential in my team not to poison or paralyze my sweepers. She also helps the team with crippling threats.
With Aromatherapy heals all Pokémon team their status, which is very useful to give more durability to the sweepers and to prevent that walls weakening fast. It also allows that Weezing uses Rest.
Flamethrower is very useful against Scizor to curb emerging Blissey.
Thunder Wave over Toxic to cripple Heatran and other threats in general.
Softboiled to recover their HP.
Revenge Killer:
Jirachi @ Choice Scarf
EV's: 80 HP / 252 Atk / 176 Spe
Nature: Jolly
~ Iron Head
~ Thunder Punch
~ Trick
~ Fire Punch
It's the Revenge Killer of the team.
Jirachi can use their skill Iron Head with Serene Grace, and thanks to Choice Scarf can almost always attack before.
Trick can be used to cripple walls or annoyers like Blissey.
Fire Punch allows it revenge killing Scizor and Thunder Punch ends with Gyarados.
Wall Breaker:
Heatran @ Life Orb / Expert Belt
Nature: Naive
EV's: 4 Atk / 252 SpA / 252 Spe
~ Fire Blast
~ Earth Power
~ Hidden Power [Grass] / Dragon Pulse
~ Explosion
Fire Blast is the main attack with STAB. This attack done enough damage to everything that does not resist.
Earth Power allows it to hit other Heatran.
I doubt between HP [Grass] to end Swampert and Dragon Pulse to threaten Dragon types.
Finally it may explode when it have few HP.
I doubt what item give it. If I give it Life Orb my oponent knowns it when I attack, while with Expert Belt I could be tricked to think that it's a ScarfTran.
Changes Made:
- Swampert to lead and SR for Waterfall.
- Jirachi to Revenge Killer and Thunder Punch for SR and Fire Punch for U-Turn.
- Weezing replaced by a Wall Breaker Heatran.
This team is very defensive. The sweepers have defensive EV's, but can hit hard after a boost. I tried to create a team that can simultaneously receive several attacks and strike hard. In my team, in addition to special / physical sweeper and special / physical wall, there is always a annoyer, a cleric and a Phazer to face the most threats.
I try not to repeat any weakness.
Lead / Physicall Wall / Phazer:

EV's: 252 HP / 252 Def / 4 Atk
Nature: Relaxed
~ Waterfall
~ Earthquake
~ Roar
~ Ice Beam
The first turn it makes Stealth Rock.
EQ as main attack and Ice Beam for Salamence mainly.
With Roar is the team Phazer and prevents the rival to increase its stats.
Special Sweeper:

Latias @ Life Orb / Leftovers
EV's: 128 HP / 128 SpA / 252 Spe
Nature: Timid
~ Surf
~ Dragon Pulse
~ Calm Mind
~ Recover
I use her as special sweeper, but I give her the EV's of the defensive set for best durability and after one Calm Mind she can do much damage anyway.
Surf and Dragon Pulse can hit at least neutral to all except Pokemon Empoleon.
Calm Mind to boost your SpD and your SpA and Recover to recover from the damage they'll shift in using Calm Mind.
Physical Sweeper:

Gyarados @ Leftovers
EV's: 156 HP / 108 Atk / 100 Def / 144 Spe
Nature: Adamant
~ Dragon Dance
~ Waterfall
~ Stone Edge
~ Taunt
I test this set and the offensive Gyarados and I obtain best results with this set.
Dragon Dance to boost its Attack and Speed.
Taunt to prevent a Phazer spoil the Dragon Dance boosts and stop the rival's walls.
As main attack Waterfall with STAB and Stone Edge for other Gyarados, Salamence and bulky waters.
Special Wall / Cleric

Blissey @ Leftovers
EV's: 252 Def / 40 SpA / 216 SpD
Nature: Calm
~ Thunder Wave
~ Flamethrower
~ Aromatherapy
~ Softboiled
She protects her teammates for status and special attacks. She is essential in my team not to poison or paralyze my sweepers. She also helps the team with crippling threats.
With Aromatherapy heals all Pokémon team their status, which is very useful to give more durability to the sweepers and to prevent that walls weakening fast. It also allows that Weezing uses Rest.
Flamethrower is very useful against Scizor to curb emerging Blissey.
Thunder Wave over Toxic to cripple Heatran and other threats in general.
Softboiled to recover their HP.
Revenge Killer:

Jirachi @ Choice Scarf
EV's: 80 HP / 252 Atk / 176 Spe
Nature: Jolly
~ Iron Head
~ Thunder Punch
~ Trick
~ Fire Punch
It's the Revenge Killer of the team.
Jirachi can use their skill Iron Head with Serene Grace, and thanks to Choice Scarf can almost always attack before.
Trick can be used to cripple walls or annoyers like Blissey.
Fire Punch allows it revenge killing Scizor and Thunder Punch ends with Gyarados.
Wall Breaker:

Heatran @ Life Orb / Expert Belt
Nature: Naive
EV's: 4 Atk / 252 SpA / 252 Spe
~ Fire Blast
~ Earth Power
~ Hidden Power [Grass] / Dragon Pulse
~ Explosion
Fire Blast is the main attack with STAB. This attack done enough damage to everything that does not resist.
Earth Power allows it to hit other Heatran.
I doubt between HP [Grass] to end Swampert and Dragon Pulse to threaten Dragon types.
Finally it may explode when it have few HP.
I doubt what item give it. If I give it Life Orb my oponent knowns it when I attack, while with Expert Belt I could be tricked to think that it's a ScarfTran.
Changes Made:
- Swampert to lead and SR for Waterfall.
- Jirachi to Revenge Killer and Thunder Punch for SR and Fire Punch for U-Turn.
- Weezing replaced by a Wall Breaker Heatran.