Half of your team has a x4 weakness to Ice, which essentially means you can be KO'ed by a Weavile w/ Ice Punch, since its 125 base speed (w/ most probable EV training) means it will almost certainly go before your entire team.
I would consider other pseudo-dragon/ dragon egg group pokemon instead, or if you're going in ubers (half of your team are ubers anyway), dragon legendaries. There is no part-dragon non-legendary except for Kingdra that doesn't have Ice weakness.
If you don't want to change your team, here's my advice:

Garchomp
@ Muscle Band/ Damp rock
Ab: Rough Skin
Role: Lead
EV: 252 Atk, 252 Speed, 4 HP
Nature: Jolly
- Crunch/ Rain Dance
- Stone Edge
- Earthquake
- Dragon Claw

Dragonite
@ Left Overs/ Expert Belt/ Damp Rock
Ab: Multiscale
Role: Rain Dance Sweeper
EV: 252 Sp. Atk, 252 Def, 4 HP
Nature: Quiet/ neutral nature
- Roost
- Hurricane
- Thunder
- Rain Dance/ Stone Edge (Rain Dance if you decide use Crunch on Garchomp)
NB: I know Dragonite's attack is higher, but a base 100 Sp. Atk isn't shabby either

Hydreigon
@ Expert Belt/ Left overs
Ab: Levitate
Role: Mixed Sweeper
EV: 252 Atk, 252 Sp. Atk, 4 HP
Nature: Neutral nature
- Crunch
- Zen Headbutt (type & fighting weakness coverage)
- Draco Meteor
- Roost/ U-Turn

Haxorus
@ Scope Lense
Ab: Mold Breaker
Role: Physical sweeper
EV: 252 Atk, 252 Speed, 4 HP
Nature: Adamant/ Jolly
- Dragon Dance
- Earthquake
- Dragon Pulse
- Brick Break

Salamence
@ Lum Berry
Ab: Intimidate/ Moxie
Role: Outrage Dragon Dance
EV: 252 Atk, 252 Speed, 4 HP
Nature: Adamant
- Outrage
- Roost
- Dragon Tail
- Dragon Dance

Druddigon
@ Leftovers
Ab: Rough Skin/ Mold Breaker
Role: Paralyse shuffler
EV: 252 Def, 252 Sp. Def, 4 Atk
Nature: Adamant
- Glare
- Dragon Tail
- Sucker Punch
- Substitute
However, this means that you have no Weavile counter, because it will out speed your fastest dragon (Garchomp).
Movesets for alternatives

Kingdra
@ Damp Rock
Ab: Sniper
Role: Rain Dance lead + sweeper
EV: 252 Sp. Atk, 128 Def, 128 Sp. Def
Nature: Quiet/ Relaxed
- Dragon Pulse
- Surf/ Scald (1st for higher power, 2nd for burn chance)
- Hydro Pump
- Rain Dance

Reshiram
@ Leftovers
Ab: Turboblaze
Role: Special Sweeper
EV: 252 Sp. Atk, 128 Def, 128 HP/ Sp. Def
Nature: Quiet/ neutral nature
- Flame Charge (speed boost)
- Dragon Pulse (STAB)
- Focus Blast (Type coverage)
- Blue Flare/ Roost (STAB/ recover, your choice)

Dialga
@ Expert Belt
Ab: Pressure
Role: Sweeper & set up
EV: 252 Sp. Atk, 252 HP, 4 Sp. Def
Nature: Quiet/ neutral nature
- Stealth Rock (Weavile protection)
- Flamethrower (type coverage)
- Draco Meteor (STAB)
- Dragon Tail

Palkia
@ Expert Belt
Ab: Pressure
Role: Sweeper
EV: 252 Sp. Atk, 252 HP, 4 Def
Nature: Quiet/ neutral nature
- Special Rend
- Aqua Tail
- Focus Blast
- Thunderbolt (Thunder w/ Rain Dance)
Pseudo-dragons

Sceptile
@ Big Root
Ab: Overgrow
Role: Drainer/ Sp. sweeper
EV: 252 Speed, 252 Sp. Atk, 4 Def
Nature: Modest/ Timid
- Giga Drain
- Leaf Storm/ Solar Beam
- Dragon Pulse
- Earthquake/ Sunny Day

Milotic
@ Leftovers
Ab: Marvel Scale
Role: Recover stall, support, shuffler
EV: 252 Def, 252 Sp. Atk, 4 Speed
Nature: Bold/ Modest
- Surf/ Scald
- Recover
- Ice Beam
- Rain Dance/ Light Screen/ Dragon Tail

Scrafty
(seriously who put you in the dragon egg group??)
@ Expert Belt
Ab: Moxie/ Intimidate
Role: Physical Sweeper
EV: 252 Atck, 128 Def, 128 Sp. Def
Nature: Adamant
- Crunch
- Drain Punch
- Stone Edge
- Zen Headbutt