Hi mister pokemon0078! Nice team.
After taking a close look at your team, I came to the conclusion that entry hazards like Stealth Rock are really a bother for your team. Scizor and Rotom-W, your VoltTurners, have to repeatedly switch in, and each time they do, you lose health due to entry hazards damage, making them less effective threats. Salamence is also less effective since it loses 25% of its health upon switching into Stealth Rock, a hazard your team fails to eliminate. To solve this problem, I would recommend a Standard Starmie
instead of Rotom-W. Starmie can still utilize powerful Electric and Water-type moves like Rotom-W, and would be a great addition to your team since it provides invaluable Rapid Spin support, while keeping an offensive presence. Hydro Pump is a powerful STAB, and Ice Beam and Thunderbolt are used as coverage moves. Leftovers allows recovery each turn, and Natural Cure heals status ailment upon switching out.
At this point, hazards wouldn't be too big of a problem. However, Terrakion is a threat, as none of your teammates can adequately tank a Close Combat without taking a lot of damage. I feel that Hydreigon's presence just compounds the Terrakion weakness. It's for this reason that I would replace it by a Swords Dance Gliscor
. Instead of having 4 special attackers and only 2 physical attackers, it's now equal at 3 per category. Gliscor helps deal with Terrakion, who can't do much to it, while Gliscor takes it out with Earthquake. Swords Dance gives it +2 in Attack, which lets it hit hard and still be able to tank hits. Earthquake is its main STAB, but Ice Fang is for coverage. Finally, Taunt allows it to prevent opponents from setting up, which gives it an advantage against an opponent like Ferrothorn, who will become a set-up fodder. Cool team, and good luck!
Starmie @ Leftovers | Natural Cure
Timid Nature | 252 SpA / 4 SpD / 252 Spe
Hydro Pump | Ice Beam | Thunderbolt | Rapid Spin
Gliscor @ Toxic Orb | Poison Heal
Impish Nature | 252 HP / 184 Def / 72 Spe
Swords Dance | Earthquake | Ice Fang | Taunt