Is there anything/any pokemon I should replace?

[WishCookie]

Ok so, I feel like I need some guidance. Is there anything I should change/replace? Do you have suggestions for other movesets/items or pokemon? Just let me know.

Vaporeon @Leftovers
Bold 252 HP/252 Def/4 Sp.Def
Water Absorb

Scald
Protect
Toxic
Wish

Medicham @Medichamite
Jolly 252 Sp/252 Atk/4 Hp
Pure Power

Substitute
Zen Headbut
Fire Punch
High Jump Kick

Cloyster @Icicle Plate
Adamant 252 Sp/252 Atk/4 Def
Skill Link

Shell Smash
Toxic Spikes
Rock Blast
Icicle Spear

Ninetales @Focus Sash
Timid 252 Sp.Atk/252 Sp/4 Def
Drought

Heat Wave
Hypnosis
Energy Ball
Nasty Plot

Klefki @Light Clay
Bold 240 Hp/160 Sp.Def/108 Def
Prankster

Light Screen
Reflect
Thunder Wave
Foul Play

Noivern @No item at the moment
Timid 252 Sp.Atk/252 Sp/4 Sp.Def
Infiltrator

Draco Meteor
Focus Blast
Flamethrower
Roost

 

[PlatinumDude]

Sylveon is the better option over Vaporeon because it has a better defensive typing to handle Dragon, Fighting and Dark Pokemon:
-Wish
-Protect
-Hyper Voice
-Heal Bell/Calm Mind
Nature: Bold
EVs: 252 HP/216 Def/40 SDef
Item: Leftovers
Ability: Pixilate

Cloyster is pretty much mediocre this time around. It doesn't have time to set up Shell Smash because of priority everywhere (Talonflame's Brave Bird in particular). Greninja is the better option over it, IMO, since it hits harder than it off the bat, though Talonflame is still a problem:
-Hydro Pump/Surf
-Ice Beam
-Extrasensory
-Dark Pulse/Hidden Power (Fire/Grass)/Grass Knot/Spikes
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Life Orb/Focus Sash
Ability: Protean

Drought doesn't benefit any of your team members. Due to the weather nerf, Ninetales is a lot less useful. Heatran is the better option in this case:
-Lava Plume
-Protect
-Taunt/Roar/Stealth Rock
-Toxic/Will-o-Wisp
Nature: Calm
EVs: 248 HP/220 SDef/40 Spe
Item: Leftovers

or
-Substitute
-Toxic
-Protect
-Lava Plume/Flamethrower/Fire Blast
Nature: Timid
EVs: 252 SAtk/12 SDef/244 Spe
Item: Leftovers

or
-Overheat/Fire Blast
-Flash Cannon
-Stone Edge/Earth Power
-Flamethrower/Fire Blast/Hidden Power (Ice)
Nature: Modest
EVs: 252 SAtk/4 SDef/252 Spe
Item: Choice Scarf

Spikes is the better option over Thunder Wave on Klefki if you didn't opt for Spikes on Greninja:
-Reflect
-Light Screen
-Spikes
-Play Rough/Foul Play
Nature: Impish/Bold
EVs: 252 HP/252 Def/4 SDef
Item: Light Clay
Ability: Prankster

Noivern is kinda meh in OU, since it doesn't have much power compared to fellow Dragon Pokemon Dragonite and Charizard X. I think the former should be used:
-Dragon Dance
-Outrage/Dragon Claw
-Earthquake
-Extreme Speed
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Lum Berry/Weakness Policy
Ability: Multiscale

or
-Outrage
-Earthquake
-Extreme Speed
-Fire Punch/Dragon Claw
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Choice Band
Ability: Multiscale

or
-Dragon Claw
-Earthquake
-Extreme Speed
-Roost
Nature: Adamant
EVs: 216 HP/64 Atk/228 SDef
Item: Leftovers
Ability: Multiscale

This team needs Rapid Spin support regardless if you stick to Noivern (for some reason) or Dragonite. Excadrill is the one to do this:
-Earthquake
-Iron Head
-Rapid Spin
-Rock Slide/Stealth Rock
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Leftovers/Air Balloon
Ability: Mold Breaker

or
-Earthquake
-Iron Head
-Rock Slide
-Rapid Spin
Nature: Adamant/Jolly
EVs: 252 Atk/4 Def/252 Spe (Choice Scarf) or 120 HP/136 Atk/252 SDef (Assault Vest; Adamant only)
Item: Choice Scarf/Assault Vest
Ability: Mold Breaker