Is my OU team good? What should I change?

[OreoMaster]

Okay, so recently I've been playing with this team and it's doing amazingly good in OU. It started as a fun team, you know those teams you make just for fun, but it turned out to be one of the best teams I've ever made. Being a fun team I only used the Pokemon I liked so only two of them are OU. Seriously. The problem is that I want a Rapid Spinner badly. I always find myself in so much trouble when the opponent set ups those spikes. SR isn't much of a pain and Toxic Spikes are taken care of by the should-be-OU Amoonguss.
Here is the team:
(there has been an update in the simulator so I don't know how to export it yet so I am gonna type it myself)


Hippowdon(Gaia) - Sand Force ( I need my leftovers)
Leftovers
Impish - 252 HP/224 Def/ 32 Att
SR
Earthquake
Roar
Slack Off

Blissey( Sante) - Natural Cure
Leftovers
Calm - 22 HP/ 252 Def/ 234 Sp.Def/ 4 Sp
Softboiled
Thunder Wave
Aromatherapy
Seismic Toss

Amoonguss( Chavenin) - Regenerator
Leftovers
Bold - 204 HP/ 172 Def/ 134 Sp.Def
Spore
Giga Drain
Clear Smog
HP Ice

Manetric( Levisk) - Lightningrod
Choice Scarf
Modest - 14 Def/ 252 Sp.Att/ 244 Sp
Volt Switch
HP Ice
Overheat
Switcheroo

Vaporeon( Siren) - Water Absorb
Leftovers
Bold - 236 HP/ 252 Def/ 4 Sp.Att/ 16 Sp.Def
Scald
Ice Beam
Wish
Protect

Mandibuzz( Vultina) - Overcoat
Leftovers
Careful - 236 HP/ 82 Def/ 192 Sp.Def
Roost
Brave Bird
Whirlwind
Knock Off

That's it. Yeah the coloring is awesome!! :D
Anyway, here are some things I would like you to have in mind before posting your hopefully useful advice.

1. The most useful Pokemon of the team are Amoonguss and Blissey so I'm not changing them.
2. Roar/Whirlwind, Clear Smog/ Haze, Knock Off, Rapid Spin, Aromatherapy, Wish and a Pokemon to remove Toxic Spikes as soon as it switches in are very necessary.
3. I wouldn't really mind changing Manetric but he is the only offensive one and Switcheroo has come in handy so many times it isn't even funny anymore.

That's it and thanks for your help! :D

 

[PlatinumDude]

On Hippowdon, Sand Force is absolutely useless unless you're using Tyranitar alongside it. Even then, Landorus does a better job at Sand Force sweeping because of higher Attack and Speed. Donphan can lay down Stealth Rock and spin away opposing hazards:
-Stealth Rock
-Rapid Spin
-Earthquake
-Roar/Toxic/Knock Off
Nature: Impish
EVs: 252 HP/4 Atk/252 Def
Item: Leftovers
Ability: Sturdy

or
-Rapid Spin
-Earthquake
-Stone Edge/Head Smash/Fire Fang
-Ice Shard/Stealth Rock
Nature: Adamant
EVs: 252 HP/252 Atk/4 Def
Item: Leftovers
Ability: Sturdy

On Amoonguss, it's better with a specially defensive spread, since some of its resists come from that end (252 HP/40 Def/216 SDef)

Manectric is seriously outclassed by Jolteon and Rotom-W. The former is faster and hits a bit harder than Manectric does; the latter has more bulk and a secondary STAB to use. Sure, Manectric has a niche of using Fire moves, but those two are better options. But then again, you have a pretty big Ferrothorn weakness too. I'll suggest Heatran and Infernape too because both can deal with Ferrothorn easily:

Jolteon:
-Thunderbolt
-Volt Switch
-Signal Beam/Shadow Ball
-Hidden Power (Ice/Grass)
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Choice Specs/Life Orb
Ability: Volt Absorb

Rotom-W:
-Thunderbolt/Volt Switch
-Hydro Pump
-Hidden Power (Ice/Fire)
-Trick
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Choice Specs/Choice Scarf

or
-Volt Switch/Thunderbolt
-Hydro Pump
-Will-o-Wisp/Hidden Power (Fire)
-Pain Split
Nature: Modest
EVs: 112 HP/252 SAtk/144 Spe
Item: Leftovers

or
-Substitute
-Pain Split
-Thunderbolt
-Hydro Pump
Nature: Modest
EVs: 236 SAtk/20 SDef/252 Spe
Item: Life Orb

Heatran:
-Lava Plume
-Toxic/Will-o-Wisp
-Roar/Stealth Rock
-Protect
Nature: Calm
EVs: 248 HP/252 SDef/8 Spe
Item: Leftovers

or
-Fire Blast
-Earth Power
-Hidden Power (Grass/Ice)
-Stealth Rock/Taunt/Roar/Flame Charge/Substitute
Nature: Modest/Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Life Orb/Air Balloon

Infernape:
-Overheat/Fire Blast
-Close Combat
-Stone Edge/Mach Punch
-Grass Knot/U-turn
Nature: Hasty/Naive
EVs: 252 Atk/4 SAtk/252 Spe
Item: Life Orb

Change Vaporeon's EV spread to a more physically defensive oriented one; its Special bulk is good enough already (248 HP/252 Def/8 SDef).

While Mandibuzz does have its merits in OU (great bulk, annoying support moves to use against the opponent), its low Attack means that it won't hit anything hard with Brave Bird. You can consider Skarmory for its incredible physical bulk, or Reuniclus for a way to break down stall:

Skarmory:
-Spikes
-Whirlwind
-Roost
-Brave Bird/Taunt
Nature: Impish/Careful
EVs: 252 HP/232 Def/20 Spe or 252 HP/232 SDef/20 Spe
Item: Leftovers/Shed Shell
Ability: Sturdy

Reuniclus:
-Calm Mind
-Psychic/Psyshock
-Focus Blast
-Recover
Nature: Bold
EVs: 252 HP/252 Def/4 SDef
Item: Life Orb/Leftovers
Ability: Magic Guard