Where do you get your EV spreads from?
Alakazam is simply too frail to set up Calm Mind. It's better off as an all-out attacker; replace CM with Substitute to block status or to scout switch ins or Hidden Power Fire/Ice for Ferrothorn/Forretress/Scizor and Dragonite/Salamence respectively. I'd rather not use both Signal Beam and Shadow Ball at once because Alakazam is walled by Steels otherwise and both already hit other Psychics supereffectively and that's redundant. Use Focus Blast over one of them. Sure, the accuracy is annoying, but Alakazam needs the Fighting coverage for Steels.
While Hydreigon's defenses are decent, Dragonite is better at running bulky spreads because of Multiscale. Hydreigon is also meant to be an all-out attacker rather than a defender. Don't bother with White Herb unless you use Shell Smash; the stat drops from Draco Meteor can be reset by switching:
-Draco Meteor
-Fire Blast
-Superpower
-Earth Power/Earthquake/Dark Pulse/Roost/Tailwind
Nature: Rash/Mild
EVs: 4 Atk/252 SAtk/252 Spe
Item: Life Orb/Expert Belt
Or
-Substitute
-Dragon Pulse
-Focus Blast
-Fire Blast/Roost
Nature: Modest
EVs: 4 HP/252 SAtk/252 Spe
Item: Leftovers/Life Orb
Or
-Draco Meteor
-Fire Blast
-Focus Blast
-U-turn/Dark Pulse
Nature: Modest
EVs: 4 HP/252 SAtk/252 Spe
Item: Choice Specs
Archeops is terrible in OU not only because of its ability, but also because of its bad defenses that make it more likely for its ability to trigger. I'd have Scizor instead, for its good synergy with Hydreigon:
-U-turn
-Bullet Punch
-Superpower
-Pursuit/Quick Attack
Nature: Adamant
EVs: 248 HP/252 Atk/8 SDef
Item: Choice Band
Ability: Technician
Or
-Swords Dance
-Bullet Punch
-Superpower/Brick Break
-Bug Bite
Nature: Adamant
EVs: 252 Atk/4 SDef/252 Spe
Item: Life Orb/Leftovers
Ability: Technician
Or
-Swords Dance
-Bullet Punch
-Bug Bite/Superpower
-Roost
Nature: Adamant
EVs: 252 HP/40 Atk/216 SDef
Item: Leftovers
Ability: Technician
If you want to keep Archeops, don't use Rock Polish on it, as it's fast enough already:
-Stone Edge
-Acrobatics
-Earth Power/Earthquake
-U-turn
Nature: Naive
EVs: 252 Atk/4 SAtk/252 Spe
Item: Flying Gem
Flying Gem boosts Acrobatics' power, making it a strong move after Archeops uses up the Gem, since Acrobatics gets stronger if the user isn't holding anything.
Your current Heatran set is illegal; only Quiet Heatran can have Eruption, due to the event setting it that way; Eruption Heatran should only be used in Trick Room teams. Even if that set was legal, Eruption on a defensive Heatran won't work because it weakens the lower Heatran's HP goes. Heatran should use these sets; Flash Cannon has poor coverage with Heatran's Fire STAB, so don't bother with it:
-Fire Blast
-Earth Power
-Hidden Power (Ice/Grass)
-Stealth Rock/Flame Charge/Taunt/Toxic
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Leftovers/Air Balloon
Ability: Flash Fire
Or
-Lava Plume
-Protect
-Roar
-Stealth Rock/Toxic/Will-o-Wisp
Nature: Calm
EVs: 248 HP/252 SDef/8 Spe
Item: Leftovers
Ability: Flash Fire
Or
-Overheat/Fire Blast
-Earth Power
-Flamethrower
-Hidden Power (Ice)/Dragon Pulse
Nature: Modest
EVs: 112 HP/160 SAtk/236 Spe
Item: Choice Scarf
Ability: Flash Fire
Or
-Fire Blast/Overheat
-Earth Power
-Dragon Pulse/Hidden Power (Ice)
-Flamethrower/Hidden Power (Grass)
Nature: Modest/Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Choice Specs
Ability: Flash Fire
Change Blissey's EV spread to 4 HP/252 Def/252 SDef to help it take physical hits better.
Skarmory is currently Taunt bait. Your current EV spread doesn't make use of its good defenses. It's also recommended you use one hazard on it at a time to make room for more important moves:
-Spikes/Stealth Rock
-Whirlwind
-Roost
-Brave Bird/Taunt
Nature: Impish/Careful
EVs: 224 HP/252 Def/32 SDef or 224 HP/32 Def/252 SDef
Item: Leftovers/Shed Shell
Ability: Sturdy
Or
-Stealth Rock
-Spikes
-Brave Bird
-Taunt
Nature: Jolly
EVs: 252 Atk/4 Def/252 Spe
Item: Custap Berry
Ability: Sturdy
I also noticed that this team is extremely vulnerable to Fighting Pokemon like Terrakion, Breloom and Conkeldurr. Alakazam and Skarmory are the only ones who can stand up to them I'm afraid. Some other Pokemon to consider are Dragonite, Therian Landorus, Jellicent and Volcarona:
Dragonite:
-Dragon Dance
-Outrage/Dragon Claw
-Fire Punch
-ExtremeSpeed/Earthquake/Roost
Nature: Adamant/Jolly
EVs: 252 Atk/4 SAtk/252 Spe
Item: Leftovers/Lum Berry
Ability: Multiscale
Therian Landorus:
-Stealth Rock/Gravity
-Earthquake
-Stone Edge
-U-turn
Nature: Adamant
EVs: 200 HP/64 Atk/244 Def
Item: Leftovers
Jellicent:
-Scald/Surf
-Will-o-Wisp
-Recover
-Taunt
Nature: Bold
EVs: 248 HP/216 Def/44 Spe
Item: Leftovers
Volcarona:
-Quiver Dance
-Bug Buzz
-Fire Blast/Fiery Dance
-Hidden Power (Ground)/Giga Drain
Nature: Timid/Modest
EVs: 252 SAtk/4 SDef/252 Spe
Item: Life Orb/Lum Berry
Or
-Quiver Dance
-Fire Blast/Fiery Dance
-Bug Buzz
-Roost
Nature: Timid
EVs: 240 HP/252 Def/16 Spe
Item: Leftovers
Or
-Quiver Dance
-Bug Buzz
-Fire Blast/Fiery Dance
-Rest
Nature: Modest
EVs: 160 HP/236 SAtk/112 Spe
Item: Chesto Berry
