OU team looking for advice!

[Nolafus]

I made an OU team and has recently just taken it's 3rd tournament victory, but I want more out of my team as any other competitive battler wants and so I come here for help.

Cloyster
Item: Focus Sash
Ability: Skill Link
EV's: 252 Atk, 252 Spe, 4 HP
Nature: Adamant
Shell Smash
Icicle Spear
Rock Blast
Ice Shard

Cloyster is my late game sweeper and can plow through any weakened team after a shell smash. Cloyster also doubles as my substitute breaker with those multi-hit moves.

Breloom
Item: Focus Sash
Ability: Technician
EV's: 252 Atk, 252 Spe, 4 HP
Nature: Jolly
Spore
Swords Dance
Mach Punch
Bullet Seed

Breloom is one of the most formidable pokemon in existence and my breloom is running your standard Technician set.

Metagross
Item: Leftovers
Ability: Clear Body
EV's: 252 Atk, 252 HP, 4 SpD
Nature: Jolly
Pursuit
Brick Break
Meteor Mash
Earthquake

Metagross is there to sponge dragon outrages which seem to be plentiful in the OU tier. Metagross is also very handy at forcing switches on pokemon such as Latias and Latios which means I almost always get that pursuit to deal some bonus damage.

Tentacruel
Item: Air Balloon
Ability: Liquid Ooze
EV's: 252 SpA, 252 Spe, 4 HP
Nature: Timid
Giga Drain
Ice Beam
Scald
Sludge Bomb

Tentacruel is there to counter rain teams and dragon types as well as to wreak havoc on ground types and possibly get in a burn with scald.

Volcarona
Item: Leftovers
Ability: Flame Body
EV's: 252 HP, 204 Def, 52 Spe
Nature: Timid
Quiver Dance
Giga Drain
Bug Buzz
Fiery Dance

Volcarona is my special sweeper and sun team counter. Volcarona has swept many teams and leave people saving certain pokemon until I bring it out just so they stand a chance of beating it.

Starmie
Item: Leftovers
Ability: Natural Cure
EV's: 252 SpA, 252 Spe, 4 SpD
Nature: Timid
Ice Beam
Psychic
Surf
Rapid Spin

Starmie is there for rapid spin relief for Cloyster and Breloom. Starmie also does very well against dragon types and has great type coverage for all around effectiveness.

That's my OU team and I'm sorry if the pictures were a little annoying as I thought some people would be able to interpret my team better with a little visual aid. I'm open to any advice, but I don't really like to use legendary pokemon although I will use them when necessary,

 

[PlatinumDude]

Too many Electric-weaks you have there. Half your team is weak to Electric, so Rotom-W, Jolteon, Thundurus-T and Magnezone can run right through the team.

Tentacruel should only be used for Rapid Spin/Toxic Spikes support on rain teams and nothing else. Offensive sets are outclassed by Starmie 100%. Lati@s (thanks to their typing and high Special Defense), Kingdra (who can use Swift Swim to mooch off of opposing rain) or Dragonite (courtesy of Multiscale) are several examples of better rain checks than Tentacruel:
Latias:
-Calm Mind
-Dragon Pulse
-Recover
-Psyshock/Hidden Power (Fire)/Substitute
Nature: Timid
EVs: 252 HP/4 SAtk/252 Spe
Item: Leftovers

or
-Draco Meteor
-Psyshock
-Surf/Hidden Power (Fire)
-Recover
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb

or
-Reflect
-Light Screen
-Draco Meteor
-Healing Wish
Nature: Timid
EVs: 252 HP/4 Def/252 Spe
Item: Light Clay

Latios:
-Draco Meteor
-Surf
-Psyshock
-Trick/Hidden Power (Fire)
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Choice Specs/Choice Scarf

or
-Calm Mind
-Dragon Pulse
-Surf
-Recover/Psyshock
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Leftovers/Life Orb

or
-Draco Meteor
-Psyshock
-Surf/Hidden Power (Fire)
-Recover
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Life Orb

or
-Reflect
-Light Screen
-Dragon Pulse
-Memento
Nature: Timid
EVs: 252 HP/4 Def/252 Spe
Item: Light Clay

Kingdra:
-Draco Meteor
-Hydro Pump
-Surf/Ice Beam
-Dragon Pulse/Ice Beam
Nature: Modest
EVs: 28 HP/252 SAtk/228 Spe
Item: Choice Specs
Ability: Swift Swim

or
-Substitute
-Dragon Dance
-Waterfall
-Outrage
Nature: Adamant
EVs: 40 HP/228 Atk/12 Def/228 Spe
Item: Leftovers
Ability: Swift Swim

or
-Dragon Dance
-Waterfall
-Outrage
-Rest
Nature: Adamant
EVs: 152 HP/96 Atk/32 SDef/228 Spe
Item: Chesto Berry
Ability: Swift Swim

or
-Dragon Dance
-Waterfall/Hydro Pump
-Outrage
-Draco Meteor/Hidden Power (Fire)
Nature: Naughty
EVs: 136 Atk/136 SAtk/236 Spe
Item: Life Orb/Lum Berry
Ability: Swift Swim

Dragonite:
-Dragon Dance
-Outrage/Dragon Claw
-Fire Punch
-Roost/ExtremeSpeed/Earthquake
Nature: Adamant/Jolly
EVs: 252 Atk/4 SDef/252 Spe
Item: Leftovers/Lum Berry
Ability: Multiscale

or
-Outrage
-ExtremeSpeed
-Earthquake/Superpower
-Fire Punch/Waterfall
Nature: Adamant
EVs: 252 Atk/4 SDef/252 Spe
Item: Choice Band
Ability: Multiscale

or
-Substitute
-Dragon Tail
-Thunder Wave/Flamethrower
-Roost
Nature: Careful
EVs: 252 HP/4 Def/252 SDef
Item: Leftovers
Ability: Multiscale

You need hazards, man. Metagross is capable of providing that for you. Brick Break won't cut it, and you do realize it gets Hammer Arm, right?:
-Stealth Rock
-Meteor Mash
-Hammer Arm/Earthquake
-Pursuit
Nature: Adamant
EVs: 252 HP/96 Atk/160 SDef
Item: Leftovers

It seems that Volcarona is using an all-out offensive set, so you should use this EV spread to match: 252 SAtk/4 SDef/252 Spe. I don't see what your current spread accomplishes at all. Consider Life Orb or Lum Berry as your item, as Leftovers is better suited for defensive Quiver Dance sets.

Offensive Rapid Spinning Starmie should use Psyshock over Psychic so it can get past special walls; this should show what I mean:
-Hydro Pump/Surf
-Rapid Spin
-Psyshock/Thunderbolt
-Ice Beam/Recover
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Leftovers/Life Orb
Ability: Natural Cure

Edit: a Jolly nature is better on Cloyster because Adamant Cloyster fails to outspeed several Choice Scarfed threats like Infernape and Terrakion even at +2 Speed.

 

[Nolafus]

Thanks, I changed Starmie, metagross, cloyster, and volcarona and I'm benefiting from the results. The only thing I'm struggling with is a replacement for tentacruel. I tried your suggestions, but the ice beams that go hand in hand with rain teams are devastating my "counters". Do you have any suggestions on pokemon that can counter rain teams and still be a threat without the rain?

 

[PlatinumDude]

Alright, how about Blissey?:
-Stealth Rock/Heal Bell/Aromatherapy
-Softboiled
-Seismic Toss/Flamethrower
-Toxic
Nature: Calm
EVs: 4 HP/252 Def/252 SDef
Item: Leftovers
Ability: Natural Cure

 

[Nolafus]

I played with Blissey for a while and I think I will keep it. Thanks for all you help!

 

[Musica]

Use Ice Punch on Metagross. While it can sponge those annoying Outrages, it can also deal a significant amount of damage to the Outraging Dragon.