Giga Impact is a terrible idea in doubles as it makes Mega Khangaskhan unable to attack for a turn. Replace it with Return for STAB, no negative effects, and 102 Base Power. Also, replace Shadow Claw for Sucker Punch for priority and ghost coverage. Tank Khangaskhan-Mega just doesn't work; change his EVs and Nature to Adamant Nature and give it 252 Atk/252 Spe/4 Def. Coverage in double battles doesn't matter as much as your partner can cover for you, and Aeriel Ace's Base Power sits at a disgustingly low 60, with its side effect being essentially useless in the competitive scene, so get rid of Aerial Ace and give Khangaskhan Drain Punch for recovery. Tank Noivern doesn't work either, especially not a mixed set, so change him to
Noivern @ Choice Specs
Ability: Infiltrator
Timid Nature
EVs: 252 Spe/252 SpA/4 SpD
- Draco Meteor
- Hidden Power (Fire)
- Hurricane
- Focus Miss
Sand Veil Garchomp with Sandstorm is extremely gimmicky and will never work. Instead, make him
Garchomp @ Groundinium Z
Ability: Rough Skin
Jolly Nature
EVs: 172 Atk/252 Spe/84 HP
- Earthquake
- Dragon Claw
- Protect
- Poison Jab
Also, you have Eelectross to cover your 4x Ice weakness anyways.
Safety Goggles is almost never used in competitive apart from Shedinja because it wastes an item slot just to stop 1/16 damage done to you every turn, making leftovers 100x better, except neither item suits Eeletross in particular. As for "Why not give Eelectross Coil because it raises so many stats?"
- Attack is useless as your Eelectross isn't physical
- It would extremely difficult for Eelectross to set up as it has minimal defenses
- Accuracy is useless as all of Eelectross's moves already have 100% Accuracy anyways
- Defense is almost useless as Eelectross has no recovery and isnt going to last long anyways
Instead:
Eelectross @ Assault Vest
Ability: Levitate
Modest Nature
EVs: 212 HP/44 SpA/4 Def/220 SpD/28 Spe
IVs: 0 Atk
- Flamethrower
- Thunderbolt
- Super Fang
- Flash Cannon
Acrobatics Scisor with an item is literally the worst idea ever. There's too many problems with scisor for me to list here but here's your new one
Scisor @ Choice Band
Ability: Technician
Adamant Nature
EVs: 252 Atk/120 HP/136 Spe
- Bullet Punch
- Bug Bite
- Aerial Ace
- Brutal Swing
Same with Vapeoreon:
Vaporeon @ Leftovers
Ability: Hydration
Bold Nature
EVs: 252 HP/130 Def/136 SpD
IVs: 0 Atk
- Scald
- Rain Dance
- Ice Beam
- Rest