Here are some suggestions for your team
Ok so, You have both Ferro and Skarm on the same team with the same role. We can change that.
Take out Ferrothorn and put in Gliscor.
Gliscor @ Toxic Orb
Trait: Poison Heal
EVs: 220 Hp/ 252 Def/ 36 Atk
Nature
- Substitute
- Ice Fang
- Earthquake
- Protect
Ok so you have an OU toxic stall Gliscor who works just as well in Doubles. Defensive wall with EQ and Ice Fang to take out some annoyances.
For Garchomp I would run a SD set.
Garchomp @ Yache Berry
Trait: Sand Veil
EVs: 252 Atk / 252 Spd / 4 HP
Adamant Nature
- Swords Dance
- Protect
- Rock Slide
- Dragon Claw/Rock Slide
Nice Doubles SD Chomp set. Protect allows your partner to EQ while you live on. Dragon Claw might be better for him as you will be susceptible to Wide Guard otherwise. Berry protects him from 4X ice weakness and you can protect while teammate kill of the ice user.
Scizor. We are going to replace this epic hunk of metal with a sand setter. This is essentially the team for sand so we shall have sand.
Tyranitar @ Chople Berry
Trait: Sand Stream
EVs: 252 HP / 36 Def / 96 SDef
Brave Nature
- Crunch
- Fire Punch
- Rock Slide
- Protect
Berry reduces those lovers of Mach Punch and such. EVs provide bulk. Rock Slide to hit ice types that threaten Gliscor and Chomp. Moveset provides you nearly ultimate coverage. Keep this guy alive. He is our only hope. xD
Cresselia, ahhh the favorite wall in Doubles <3
Now to business.
Cresselia @ Leftovers
Trait: Levitate
EVs: 252 HP / 184 SDef / 104 Def
Calm Nature
- Psyshock
- Hidden Power Fire
- Toxic
- Protect
A set that will allow you to toxic stall. HP Fire prevents steel types from walling while Psyshock is to take out poison types and other special walls (Blissey). 252 HP EVs to max healing from Lefties, and the other EVs to make her a special wall with some defensive bulk. paired with Gliscor I can almost guarantee that you will be causing quite a few RQs.
Excadrill is the most common poke on a sand team, and for a very good reason. His ability will also cause RQs if played right.
Excadrill @ Life Orb
Trait: Sand Rush
EVs: 252 Atk / 60 HP / 196 Spd
Adamant Nature
- Protect
- Rock Slide
- Earthquake
- X-Scissor
This set with LO boost will cause an unlimited amount of tears. X-Scissor is to take out those Cress walls and other psychic walls. EQ and RS are fairly self explanatory. Protect is for when he's close to dying and you know the opponent carries priority. Protect/teammate destroys.
Ok so now we have a water weakness. We can counter this by throwing in our favorite grass type next to Ferrothorn
CRADILY
Cradily @ Big Root
Trait: Storm Drain
EVs: 252 SAtk / 128 Def / 128 SDef
Modest Nature
- Protect
- Hidden Power Ice
- Earth Power
- Giga Drain
So this is your SAtker. Big Root allows constant boost for Giga Drain recovery. Earth Power is well fairly self explanatory. HP Ice for Drags and Flying types who want a piece of that Giga Drain and take a chunk of pain instead. Protect, well I'll explain that in a moment.
So as Blobby has mentioned, hazards are not commonly used in Doubles. Instead Protect is the big thing. Saving yourself from a double hit while your teammate smashes the opponent. For Gliscor and Cress it's more for stalling.
I was surprised as I was reading to see you were not using a sand team. All of the pokes I have suggested and that you had are mainly seen in sand teams. So I brought that to life a bit.
Always keep in mind that there is a huge difference between 2vs2 and 1vs1. What's good for the Goose is not necessarily good for the Gander.
Hope this works out for you. It may take a while to settle into your pokes, find some good leads, so on so forth.
Good Luck and have fun.