Any suggestions on improving my OU monotype water team?

>Politoed @ Leftovers
Trait: Drizzle
EVs: 252 HP / 252 Def / 4 Spd
Bold Nature
- Scald
- Ice Beam
- Encore
- Hypnosis

>Swampert @ Leftovers
Trait: Torrent
EVs: 240 HP / 16 Atk / 252 Def
Impish Nature
- Stealth Rock
- Waterfall
- Earthquake
- Toxic

>Cloyster @ Focus Sash
Trait: Skill Link
EVs: 4 HP / 252 Atk / 252 Spd
Naive Nature
- Shell Smash
- Icicle Spear
- Rock Blast
- Razor Shell

>Tentacruel @ Black Sludge
Trait: Rain Dish
Shiny: Yes
EVs: 252 HP / 236 Def / 20 Spd
Bold Nature
- Rapid Spin
- Hidden Power [Fire]
- Giga Drain
- Substitute

>Lanturn @ Leftovers
Trait: Volt Absorb
EVs: 52 HP / 252 Def / 204 Spd
Calm Nature
- Scald
- Ice Beam
- Thunderbolt
- Heal Bell

>Gyarados @ Leftovers
Trait: Intimidate
EVs: 88 HP / 248 Atk / 4 Def / 168 Spd
Jolly Nature
- Substitute
- Dragon Dance
- Waterfall
- Bounce