Infernape - Infernape can't learn Ice Punch, change it to Hidden Power [Ice], and in the last slot run Close Combar or Flare Blitz.
Dragonite - Looks good, run Dragon Claw over Outrage, and ExtremeSpeed for the last slot, as Roost is more for bulkier Dragonites. An alternative to E-speed is Earthquake, which stops you from being walled by Heatran. Also, why are you running SAtk EVs? Change those to Attack.
Salamence - Looks good, run Outrage > Fly though, Fly kind if sucks in competitive.
Garchomp - I am gonna replace Garchomp, it doesn't contribute to the team a whole lot, and it'll be replaced by Mamoswine, which synergizes well, absorbs Ice moves, and can kill other dragons.
Mamoswine @ Choice Band
Trait: Thick Fat
EVs: 252 HP / 252 Atk / 4 SDef
- Ice Shard
- Icicle Spear/Stone Edge
Magneton - Looks good, but I'm going to suggest a set that can better abuse his Eviolite bulk.
Magneton @ Eviolite
Trait: Magnet Pull
EVs: 4 HP / 252 SAtk / 252 Spd
- Charge Beam
- Hidden Power [Fire]
- Flash Cannon
Dusknoir - I don't see what Dusknoir is really doing for the team, so Ima be replacing him with Sableye, who can burn opponents, drastically increasing the bulk of your teammates, Taunt opposing walls such as Ferrothorn, and stall like a baws.
Sableye @ Leftovers
EVs: 252 HP / 120 Def / 136 SDef
- Night Shade