12 OUs, where to put them?

So, I have twelve mons for OU competition, and wanted advice for how to stack them between two teams.

Team A is currently:

Altaria @ Altarianite
Ability: Cloud Nine
EVs: 140 HP / 252 SpA / 116 SpD
Modest Nature
- Roost
- Hyper Voice
- Flamethrower
- Heal Bell

Gliscor @ Toxic Orb
Ability: Poison Heal
EVs: 184 HP / 252 Atk / 72 Spe
Adamant Nature
- Earthquake
- Knock Off
- Roost
- Swords Dance

Jirachi @ Leftovers
Ability: Serene Grace
EVs: 224 HP / 252 Atk / 32 Spe
Adamant Nature
- Iron Head
- Body Slam
- U-turn
- Zen Headbutt

Scizor (M) @ Life Orb
Ability: Technician
EVs: 248 HP / 252 Atk / 8 SpD
Adamant Nature
- Bullet Punch
- Roost
- Bug Bite
- Swords Dance

Starmie @ Leftovers
Ability: Natural Cure
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Scald
- Rapid Spin
- Psychic
- Ice Beam

Talonflame @ Sharp Beak
Ability: Flame Body
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Brave Bird
- Roost
- Will-O-Wisp
- Flare Blitz

And Team B is currently:

Excadrill @ Leftovers
Ability: Mold Breaker
EVs: 252 HP / 252 Atk / 4 SpD
Adamant Nature
- Earthquake
- Iron Head
- Rapid Spin
- Toxic

Latios @ Latiosite
Ability: Levitate
EVs: 4 HP / 252 SpA / 252 Spe
Modest Nature
- Calm Mind
- Draco Meteor
- Psychic
- Roost

Manaphy @ Leftovers
Ability: Hydration
EVs: 4 HP / 252 SpA / 252 Spe
Modest Nature
- Tail Glow
- Scald
- Ice Beam
- Energy Ball

Weavile @ Assault Vest
Ability: Pressure
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Icicle Crash
- Low Kick
- Night Slash
- Poison Jab

Sylveon @ Leftovers
Ability: Pixilate
EVs: 252 HP / 252 SpA / 4 SpD
Modest Nature
- Hyper Voice
- Shadow Ball
- Toxic
- Heal Bell

Skarmory @ Leftovers
Ability: Sturdy
EVs: 248 HP / 236 Def / 24 Spe
Impish Nature
- Spikes
- Whirlwind
- Roost
- Iron Head

Are there mons that should be switched from A to B or vice versa for better coverage?

Thanks in advance!

First off, what purpose do any of your EV spreads serve?

Team A:

Mega Altaria's EV spread should be 248 HP/168 SAtk/92 Spe, which is enough to outspeed Jolly Azumarill.

Swords Dance Gliscor should be specially defensive to better take on things like Therian Tornadus Gengar better: 244 HP/8 Def/200 SDef/56 Spe should be the spread in that case.

Jirachi should be the Stealth Rock setter of Team A, since it doesn't have a Stealth Rock user at the moment:
-Stealth Rock
-Iron Head
-U-turn
-Body Slam/Thunder Wave/Fire Punch
Nature: Careful
EVs: 252 HP/176 SDef/80 Spe
Item: Leftovers

Starmie isn't that strong and it needs all the power it can get from Hydro Pump. Scald only sees use on defensive sets:
-Hydro Pump
-Psychic/Psyshock/Thunderbolt
-Ice Beam/Hidden Power (Fire)
-Rapid Spin
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Life Orb
Ability: Natural Cure/Analytic

Team B:
Bulky Excadrill should be Careful with 252 HP/4 Atk/252 SDef to make the most out of its good defensive typing.

Latios isn't a bad Mega by any means, but there's a huge opportunity cost in using that over the more popular Megas like Charizard and Metagross. Mega Latios is only slightly weaker than Life Orb Latios in terms of damage output. Charizard should be the Mega to use, IMO:
-Dragon Dance
-Flare Blitz
-Dragon Claw
-Earthquake/Roost
Nature: Adamant/Jolly
EVs: 252 Atk/4 Def/252 Spe
Item: Charizardite X
Ability: Blaze

or
-Flare Blitz
-Dragon Claw/Earthquake
-Will-o-Wisp
-Roost
Nature: Impish
EVs: 248 HP/100 Def/160 Spe
Item: Charizardite X
Ability: Blaze

or
-Swords Dance
-Flare Blitz
-Outrage/Dragon Claw
-Tailwind/Roost
Nature: Adamant
EVs: 40 HP/252 Atk/216 Spe
Item: Charizardite X
Ability: Blaze

Assault Vest is one of the worst items to use on Weavile, as it doesn't do much to improve its special bulk. Assault Vest should only be used on Pokemon that are bulkier than Weavile is, like Azumarill or Conkeldurr. It should stick to Life Orb as the item. Knock Off is also more useful than Night Slash, as the power difference between both is negligible and it gets rid of non-Mega Stone items:
-Knock Off
-Icicle Crash
-Ice Shard
-Low Kick/Poison Jab/Pursuit
Nature: Jolly
EVs: 252 Atk/4 Def/252 Spe
Item: Life Orb
Ability: Pressure

Sylveon faces a bit of competition with Clefable as a cleric, since the latter has good utility with Unaware and more physical bulk:
-Wish
-Protect
-Moonblast
-Heal Bell
Nature: Bold
EVs: 248 HP/252 Def/8 SDef
Item: Leftovers
Ability: Unaware

If you intend to keep Sylveon, this is the set it should use so it can have more physical bulk:
-Wish
-Protect
-Hyper Voice
-Heal Bell/Toxic
Nature: Bold
EVs: 252 HP/220 Def/36 SDef
Item: Leftovers
Ability: Pixilate

What purpose does Skarmory's EV spread serve in the first place? If Skarmory doesn't outrun anything noteworthy with that spread, just stick to max HP/max Defense.