My new sand team!

Hello this is my OU sandstorm team (or what i have so far) im not sure on my 6th pokemon so advice would be great!




Tyranitar life orb
sand stream
Not sure on nature yet
or evs either
earthquake
stone edge
payback
rocksmash


Rotom-W Leftovers
levitate
Bold
252 sdef 100 HP 100 Def 50 satk
Hydro pump
tbolt
substitute
confuse ray

Ferrothorn leftovers
iron barbs
relaxed
252 HP 252 Sdef
stealth rock
leech seed
gyro ball
pow whip

Donphan leftovers
sturdy
adament
252 atk 252 HP
ice shard
rapid spin
EQ
stone edge

Mandibuzz leftovers
overcoat
impish
252 HP 252 def
whirlwind
taunt
toxic
roost

Life Orb just detracts from Tyranitar's good bulk, unless you're using Dragon Dance. It has enough bulk to set up Stealth Rock for the team:
-Stealth Rock
-Crunch
-Fire Blast
-Ice Beam/Superpower/Stone Edge
Nature: Sassy/Hasty
EVs: 252 HP/64 SAtk/192 SDef or 56 Atk/252 SAtk/200 Spe
Item: Leftovers
Ability: Sand Stream

Use Will-o-Wisp and Pain Split on Rotom-W over Subsitute and Confuse Ray. Sub in conjunction wears Rotom down over time and Confuse Ray is relatively unreliable. Use Modest and this EV spread: 112 HP/252 SAtk/144 Spe

You already have Tyranitar to set up Stealth Rock for you, like I suggested, so I'd use Landorus over Ferrothorn to take advantage of Sandstorm:
-Earthquake
-Stone Edge/Rock Slide
-U-turn
-Hidden Power (Ice)/Hammer Arm
Nature: Naive/Jolly
EVs: 252 Atk/4 Def/252 Spe
Item: Choice Scarf

Skarmory outclasses Mandibuzz in OU; it can actually hit back with Brave Bird:
-Brave Bird
-Spikes
-Roost
-Whirlwind
Nature: Impish/Careful
EVs: 252 HP/232 Def/24 Spe or 252 HP/252 SDef/24 Spe
Item: Leftovers
Ability: Sturdy

I'd recommend Virizion in the last slot, since it has good synergy with Tyranitar; it can help against bulky Water Pokemon:
-Calm Mind
-Giga Drain
-Focus Blast
-Hidden Power (Ice)
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Leftovers/Life Orb

What about a wish jirachi in the last slot it could heal the team and not get damaged by sand.