I have spent a lot of time working on it. I want to see other people's opinions.
Team at a Glance
Swampert @ Damp Rock
Ability: Torrent
Nature: Adamant
EVs: 252 Attack/252 Sp. Defense/4 HP
-Rain Dance
-Stealth Rock
-Waterfall
-Avalanche
This particular Swampert is going to be my lead. His defensive stats are great so he would be able to set up Rain Dance after he is hit. He will also mostly likely survive another hit, which allows him to set up Stealth Rock. After setting up those two moves, I would either switch him out or keep him in to fight. The reason why I did not put Earthquake on him is because Steel-type Pokemon are not a big threat. Avalanche is used because of his 4x weakness: Grass.
Kabutops @ Life Orb
Ability: Swift Swim
Nature: Adamant
EVs: 252 Attack/252 Defense/4 Speed
-Swords Dance
-Rain Dance
-Waterfall
-Rock Slide
My physical sweeper. It seems like this Kabutops can cause major destruction in the rain because of his Swift Swim. Swords Dance and Waterfall sounds like a great combination. Rain Dance is there just in case Swampert's finishes. Rock Slide is for an accurate STAB attack.
Milotic @ Leftovers
Ability: Marvel Scale
Nature: Bold
EVs: 252 HP/252 Defense/4 Sp. Attack
-Recover
-Mirror Coat
-Surf
-Ice Beam
The Pokemon that every Water-type team needs. Milotic's amazing defensive stats allows her to switch in at almost any time. Surf will benefit greatly in the rain, while Ice Beam takes out the Choiced-Outraging-Dragons. Mirror Coat is for reflecting opposing Magnezones or other Thunder-using Pokemon who benefit in the rain. Recover is there to help keep Milotic alive.
Lanturn @ Leftovers
Ability: Volt Absorb
Nature: Bold
EVs: 252 HP/252 Defense/4 Sp. Attack
-Confuse Ray
-Rain Dance
-Surf
-Thunder
Omastar @ Damp Rock
Ability: Swift Swim
Nature: Modest
EVs: 252 Sp. Attack/252 Defense/ 4 Speed
-Rain Dance
-Surf
-Ice Beam
-Hidden Power Electric
Omastar makes the perfect Special Sweeper because of Swift Swim and the high Special Attack. Surf-Ice Beam-Hidden Power Electric makes the best type coverage for any Pokemon. The 252 Defense is to boost the impressive Defense stat to block against Outraging dragons.
Ludicolo @ Leftovers
Ability: Rain Dish
Nature: Modest
EVs: 252 HP/252 Sp. Defense/ 4 Sp. Attack
-Rain Dance
-Leech Seed
-Surf
-Grass Knot
A Rain Dance team would not be complete without Ludicolo. With Rain Dish, Leftovers, and Leech seed, Ludicolo would gain 1/4 of its HP after every turn! Surf is for the STAB and boost in the rain while Grass Knot hits opposing water Pokemon. Sp. Defense helps defend against opposing Special sweepers.
Team at a Glance







Swampert @ Damp Rock
Ability: Torrent
Nature: Adamant
EVs: 252 Attack/252 Sp. Defense/4 HP
-Rain Dance
-Stealth Rock
-Waterfall
-Avalanche
This particular Swampert is going to be my lead. His defensive stats are great so he would be able to set up Rain Dance after he is hit. He will also mostly likely survive another hit, which allows him to set up Stealth Rock. After setting up those two moves, I would either switch him out or keep him in to fight. The reason why I did not put Earthquake on him is because Steel-type Pokemon are not a big threat. Avalanche is used because of his 4x weakness: Grass.

Kabutops @ Life Orb
Ability: Swift Swim
Nature: Adamant
EVs: 252 Attack/252 Defense/4 Speed
-Swords Dance
-Rain Dance
-Waterfall
-Rock Slide
My physical sweeper. It seems like this Kabutops can cause major destruction in the rain because of his Swift Swim. Swords Dance and Waterfall sounds like a great combination. Rain Dance is there just in case Swampert's finishes. Rock Slide is for an accurate STAB attack.

Milotic @ Leftovers
Ability: Marvel Scale
Nature: Bold
EVs: 252 HP/252 Defense/4 Sp. Attack
-Recover
-Mirror Coat
-Surf
-Ice Beam
The Pokemon that every Water-type team needs. Milotic's amazing defensive stats allows her to switch in at almost any time. Surf will benefit greatly in the rain, while Ice Beam takes out the Choiced-Outraging-Dragons. Mirror Coat is for reflecting opposing Magnezones or other Thunder-using Pokemon who benefit in the rain. Recover is there to help keep Milotic alive.

Lanturn @ Leftovers
Ability: Volt Absorb
Nature: Bold
EVs: 252 HP/252 Defense/4 Sp. Attack
-Confuse Ray
-Rain Dance
-Surf
-Thunder
Although she has similar EVs as Milotic, Lanturn's role on the team is different. Every Rain Dance team needs at least one Thunder-user. Lanturn is perfect because she can use Confuse Ray to help stall an opponent that is about to use Substitute. Then she will use Thunder, which will hopefully paralyze the opponent to cause the extremely annoying Confused-Paralyzed condition.

Omastar @ Damp Rock
Ability: Swift Swim
Nature: Modest
EVs: 252 Sp. Attack/252 Defense/ 4 Speed
-Rain Dance
-Surf
-Ice Beam
-Hidden Power Electric
Omastar makes the perfect Special Sweeper because of Swift Swim and the high Special Attack. Surf-Ice Beam-Hidden Power Electric makes the best type coverage for any Pokemon. The 252 Defense is to boost the impressive Defense stat to block against Outraging dragons.

Ludicolo @ Leftovers
Ability: Rain Dish
Nature: Modest
EVs: 252 HP/252 Sp. Defense/ 4 Sp. Attack
-Rain Dance
-Leech Seed
-Surf
-Grass Knot
A Rain Dance team would not be complete without Ludicolo. With Rain Dish, Leftovers, and Leech seed, Ludicolo would gain 1/4 of its HP after every turn! Surf is for the STAB and boost in the rain while Grass Knot hits opposing water Pokemon. Sp. Defense helps defend against opposing Special sweepers.