-I wouldn't use Acrobatics on Mienshao. I get that the Flying Gem Acro combo is popular/ in vogue or whatever right now, but it's not STAB, Mienshao could use a permanent item, e.g. Life Orb, and also Fake Out. It's a good move that can allow you to see what your opponent is holding (Toxic/ Flame Orb, Leftovers etc.)
-Give Metagross Bullet Punch instead of Earthquake. Mamoswine already has that.
-Mamoswine NEEDS Ice Shard. It's +1 priority and STAB.
-Houndoom would be better if you bred Sucker Punch on it (another +1 STAB), but give it Nasty Plot instead. Dark Pulse and Shadow Ball cover the same thing.
-Replace Ampharos with Jolteon. More useful ability that negates Thunder Wave, and much faster with higher sp. atk.
Mienshao @ Life Orb
Ability: Regenerator
EVs: 252 Atk, 252 Speed, 4 HP
Nature: Adamant/ Jolly
- Fake Out
- Hi-Jump Kick
- Stone Edge
- U-Turn
Standard Mienshao set, not much to say.
Metagross @ Leftovers
Ability: Clear Body
EVs: 164 HP, 252 Atk, 92 Speed
Nature: Adamant
- Meteor Mash
- Bullet Punch
- Zen Headbutt
- Ice/ Thunder Punch
Ice or Thunder Punch, doesn't really matter. Either Skarmory of Gliscor will wall you, whichever you choose. You already have Ice types with Mamoswine & Electric types with Jolteon.
Mamoswine @ Life Orb
Ability: Oblivious (Thick Fat would be better, but you don't have Dream World, and Hidden Grotto chances are slim)
EVs: 252 Atk, 252 Speed, 4 HP
Nature: Jolly
- Ice Shard
- Icicle Crash
- Earthquake
- Stealth Rock/ Super Power
Stealth Rock for some hazards or Super Power for coverage, your choice. Thick fat would be a better ability, because then Mamoswine would be taking fire damage at x1 and Ice at x1/2.
Togekiss @ Leftovers
Ability: Serene Grace
EVs: 248 HP, 216 Def, 44 Speed
Nature: Bold
- Roost
- Thunder Wave
- Air Slash
- Heal Bell/ Aura Sphere
This is the wall set. Heal Bell to cure status and continue paraflinching, or Aura Sphere to cover Rock & Steel types.
Houndoom @ Life Orb
Ability: Flash Fire
EVs: 252 Sp. Atk, 252 Speed, 4 HP
Nature: Modest/ Hasty (for Sucker Punch)
- Flamethrower
- Dark Pulse
- HP Grass
- Nasty Plot (Sucker Punch would be better)
Jolteon @ Air Balloon/ Choice Specs
Ability: Volt Absorb
EVs: 252 Sp. Atk, 252 Speed, 4 HP
Nature: Timid/ Modest
- Volt Switch
- Thunderbolt
- Shadow Ball/ Signal Beam
- HP Ice
Problems
- 2 Stealth Rock weaknesses and no spinner
- 3 Ground weaknesses
- 2 Fighting weaknesses
- 2 Water weaknesses
Suggestions
Jellicent @ Leftovers
Ability: Water Aborb
EVs: 244 HP, 216 Def, 44 Speed
Nature: Bold
- Recover
- Will-O-Wisp
- Scald
- Taunt/ Shadow Ball
Jellicent will be your wall for Water and Fighting weaknesses. It's got great typing, an ability that makes Water moves x0 and a reliable recovery method.
Hitmontop @ Leftovers
Ability: Intimidate
EVs: 252 HP, 252 Def, 4 Speed
Nature: Impish
- Rapid Spin
- Toxic
- Close Combat
- Foresight/ Stone Edge
I think Hitmontop will be a good option for your team, despite adding another Flying & Psychic weakness (which Metagross can wall anyway). Foresight isn't as useless, because you can hit spin blockers like Sableye with that move.
I would suggest you replace either Houndoom or Jolteon with one of these two.