So I made a team...

Talonflame @ Sharp Beak
Ability: Gale Wings
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Swords Dance
- Flare Blitz
- Brave Bird
- Roost

Pidgeot-Mega @ Pidgeotite
Ability: No Guard
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Hurricane
- Defog
- Heat Wave
- U-turn

Umbreon @ Lum Berry
Ability: Synchronize
EVs: 4 Atk / 252 Def / 252 Spe
Impish Nature
- Heal Bell
- Foul Play
- Wish
- Protect

Metagross @ Leftovers
Ability: Clear Body
EVs: 252 Def / 252 SpD
Sassy Nature
- Ice Punch
- Meteor Mash
- Earthquake
- Reflect

Skarmory @ Leftovers
Ability: Sturdy
EVs: 248 HP / 236 Def / 24 Spe
Bold Nature
- Spikes
- Stealth Rock
- Roar
- Toxic

(Insert another 'mon here)

So, anything major I missed out? What about the last pokemon? Gimme all the criticism!

Edit: What would I need to cover those yucky Flying and Steel types' weaknesses?
Also - I had a look at this and ew, weaknesses.

Umbreon is outclassed as a Wish passer by Sylveon and Clefable because the former has better offensive presence with Pixilated Hyper Voices and the latter has excellent utility in stopping setup sweepers cold with Unaware:

Sylveon:
-Wish
-Protect
-Hyper Voice
-Heal Bell/Toxic
Nature: Bold
EVs: 252 HP/220 Def/36 SDef
Item: Leftovers
Ability: Pixilate

Clefable:
-Wish
-Protect
-Moonblast
-Heal Bell/Thunder Wave
Nature: Bold
EVs: 248 HP/252 Def/8 SDef
Item: Leftovers
Ability: Unaware

Wash Rotom is an excellent teammate to use to help with the Flying weakness. Since Talonflame and Pidgeot are frail, a slow Volt Switch from Wash Rotom helps get them in battle safely:
-Volt Switch
-Hydro Pump
-Will-o-Wisp
-Pain Split/Rest
Nature: Bold
EVs: 248 HP/252 Def/8 Spe
Item: Leftovers/Chesto Berry

For the most part, Mega Metagross is better than regular Metagross because of Tough Claws-powered attacks. If you really must use non-Mega Metagross, Assault Vest is the way to do it. It gives it better special bulk to make good use of its resistances. Reflect should be used alongside Light Screen, IMO, but Metagross isn't the kind of Pokemon that does this sort of thing:
-Meteor Mash
-Zen Headbutt/Earthquake
-Bullet Punch
-Pursuit
Nature: Adamant
EVs: 252 HP/160 Atk/96 SDef
Item: Assault Vest
Ability: Clear Body

Or you can use Heatran instead; while it doesn't stack weaknesses with Skarmory, the shared Water weakness with Talonflame could be a problem, though you have Wash Rotom to take care of that to an extent:
-Stealth Rock
-Lava Plume
-Toxic
-Taunt/Protect/Roar
Nature: Calm
EVs: 248 HP/192 SDef/68 Spe
Item: Leftovers

or
-Magma Storm
-Earth Power
-Taunt
-Toxic/Solar Beam
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Leftovers/Air Balloon/Power Herb

or
-Fire Blast
-Flash Cannon/Stone Edge/Hidden Power (Ice)
-Earth Power
-Stealth Rock
Nature: Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Air Balloon

or
-Overheat/Fire Blast
-Flash Cannon
-Earth Power/Hidden Power (Ice)
-Stone Edge/Ancient Power
Nature: Timid
EVs: 28 HP/252 SAtk/228 Spe
Item: Choice Scarf

Skarmory should at least run an offensive move so it isn't Taunt bait. Brave Bird or Counter are the ideal options. Also, Whirlwind is superior to Roar, as it isn't blocked by the odd Soundproof:
-Spikes/Stealth Rock
-Brave Bird/Counter
-Whirlwind/Taunt
-Roost
Nature: Impish/Bold
EVs: 252 HP/252 Def/4 SDef
Item: Leftovers/Rocky Helmet
Ability: Sturdy

or
-Iron Head
-Spikes/Stealth Rock
-Whirlwind/Taunt
-Roost
Nature: Careful
EVs: 252 HP/4 Def/252 SDef
Item: Leftovers
Ability: Sturdy

Thanks for the help, I'l experiment with those.

PlatinumDude said:

Umbreon is outclassed as a Wish passer by Sylveon and Clefable because the former has better offensive presence with Pixilated Hyper Voices and the latter has excellent utility in stopping setup sweepers cold with Unaware:

Click to expand...

This is misleading. Its like comparing apples to oranges js. :|

Id go with Defog on Skarm over Spikes too. You dont have a Spin blocker/anything to capitalize on foe Defog so there is no point in using Spikes. This is amplified by the fact you are using your own Defog which is counter productive with Spikes. Using Defog on Skarm leaves you with a slot for the superior Roost on M-Pidgeot.

Also Dugtrio is a very good partner to Talon and M-Pidgeot. It removes basically every relevant counter they have (Chansey, Tar, Tran etc) with Arena Trap apart from Rotom-W and M-Pidge lures all of the aforementioned and gets dug in safely with U-Turn.

Dugtrio@Focus Sash
252 Atk / 252 Speed / 6 hp
Jolly Nature
Trait: Arena Trap
- Substitute
- Reversal
- Earthquake
- Toxic

Is my fav set on it.

Thank you Dark Azelf! I'll try out Dugtrio and see how it works out. I really appreciate the help!