How to improve this PokeBank OU team?

[Nah]

I have this team that's been working pretty well so far on Showdown. However, it does have its issues, and I'd like to hear what you all have to say about the team and how I can make it better.

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-Hydreigon w/Choice Specs
Nature: Hasty
Ability: Levitate
EVs: 252 Sp.attack, 252 Speed, 4 Sp.Defense
Moves: Draco Meteor, Fire Blast, Dark Pulse, Flash Cannon

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-Scarlet (Volcarona) w/Life Orb
Nature: Modest
Ability: Flame Body
EVs: 252 Sp.Attack, 252 Speed, 4 Defense
Moves: Bug Buzz, Quiver Dance, Giga Drain, Fiery Dance

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-Gastrodon w/Leftovers
Nature: Relaxed
Ability: Storm Drain
EVs: 252 HP, 252 Defense, 4 Sp.Defense
Moves: Scald, Toxic, Recover, Earthquake

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-Togekiss w/Leftovers
Nature: Bold
Ability: Serene Grace
EVs: 252 HP, 248 Defense, 8 Sp.Defense
Moves: Air Slash, Thunder Wave, Roost, Dazzling Gleam


-Mega Aggron w/Aggronite
Nature: Impish
Ability: Filter
EVs: 252 HP, 252 Sp.Defense, 4 Attack
Moves: Iron Head, Thunder Wave, Roar, Stealth Rock

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-Gyarados w/Leftovers
Nature: Adamant
Ability: Intimidate
EVs: 156 HP, 72 Attack, 96 Defense, 184 Sp.Defense
Moves: Waterfall, Dragon Dance, Bounce, Taunt

So, any suggestions? And yes, I know I have a Stealth Rock weakness on this team; I don't know which spinner/defogger would be a good fit, and who it would replace. 2 other things: Volcarona stays, and I'm not changing Gyarados's set (if it stays on the team).

Other than that, any and all suggestions and fixes are welcome and appreciated!

 

[PlatinumDude]

Since you want Volcarona to stay on the team that badly, I'd suggest Starmie and Excadrill as Rapid Spinners (because of their good defensive synergy):

Starmie:
-Hydro Pump/Surf
-Psyshock/Thunderbolt
-Ice Beam
-Rapid Spin
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Life Orb/Leftovers
Ability: Natural Cure

or
-Scald
-Rapid Spin
-Psyshock/Thunderbolt/Ice Beam
-Recover
Nature: Timid
EVs: 248 HP/32 Def/4 SAtk/224 Spe
Item: Leftovers
Ability: Natural Cure

Excadrill:
-Earthquake
-Rock Slide
-Rapid Spin
-Shadow Claw/Swords Dance
Nature: Adamant/Jolly
EVs: 252 Atk/4 Def/252 Spe
Item: Life Orb/Leftovers/Assault Vest/Air Balloon
Ability: Mold Breaker

Test out which one works for you.

 

[Nah]

Alright, but who has to leave to make room for the spinner? I'm not sure who to replace...

 

[PlatinumDude]

Alright, but who has to leave to make room for the spinner? I'm not sure who to replace...

Starmie can go over Gyarados. This frees the team of a Stealth Rock-weak Pokemon.