How can I improve this Uber team?

Question

Tier: Uber (1v1, not doubles)

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Kyurem-White @ Life Orb
Ability: Turboblaze
EVs: 252 HP / 4 Def / 252 SpA
Modest Nature
- Earth Power
- Draco Meteor
- Roost
- Ice Beam
Since Primal Groudon is the king of Uber and also weak to itself, Kyurem White can easily get rid of Primal Groudon using this set. It's able to take an Earthquake and it outspeeds most of them (speedy variants are very rare on Pokemon Showdown). Earth Power or Draco Meteor will certainly deal with it. It can also threaten various other Pokemon due to its STAB combination, allowing it to hit hard and heal using Roost. It's the core of the team because of those qualities.

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Magearna @ Leftovers
Ability: Soul-Heart
EVs: 252 HP / 252 SpA / 4 SpD
Modest Nature
- Fleur Cannon
- Flash Cannon
- Heal Bell
- Heart Swap
It deals with a good amount of Kyurem's problems. Heal Bell is for healing status since some Pokemon on the team may struggle against status conditions. Heart Swap is for Geomancy Xerneas.

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Groudon-Primal @ Red Orb
Ability: Desolate Land
EVs: 252 HP / 252 Atk / 4 Def
Adamant Nature
- Earthquake
- Fire Punch
- Swords Dance
- Toxic
Kyurem patches Primal Groudon's ground weakness and water weakness. Swords Dance is to set up whenever the opportunity arises. Toxic is there as a last resort in case it can't set up and it can't deal a good amount of damage. Might replace it, but I don't know what to replace it with.

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Lugia @ Leftovers
Ability: Pressure
EVs: 252 HP / 128 Def / 128 SpD
Bold Nature
- Ice Beam
- Defog
- Thunder Wave
- Recover
Kyurem-White struggles with Stealth Rock, so Defog gets rid of that. Ice Beam is there to deal a bit of chip damage. Thunder Wave halves speed, so it can be very helpful for most, if not all team members. Recover is for recovery. It's just there for support.

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Mewtwo-Mega-Y @ Mewtwonite Y
Ability: Insomnia
EVs: 252 SpA / 4 SpD / 252 Spe
Modest Nature
- Psystrike
- Shadow Ball
- Aura Sphere
It dishes out damage, what can I say? Most of the weaknesses are covered.

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Arceus @ Leftovers
Ability: Multitype
EVs: 252 HP / 4 Def / 252 Spe
Timid Nature
- Perish Song
- Whirlpool
- Protect
- Recover
It can basically take out almost any Pokemon. It's normal type because it has the least amount of weaknesses. I believe that after taking out a Pokemon, switching into Magearna will give it a special attack boost.

Comments

Give Kyurem a choice specs for more power and 4 Def/252 SpA/252 Spe timd for more speed. Replace its roost with fusion flare to cover steel, grass, and bug. Give Magearna 252 HP/4 Def/252 SpD calm to take hits more reliably. Replace its heal bell with pain split to heal. Replace Groudon's earthquake, swords dance, and toxic with precipice blades for more power, stealth rock to hurt stuff that switches, and roar to prevent opponents from setting up. Give Lugia multiscale to take hits better. Replace its defog, thunder wave, and recover with toxic to cripple defensive Pokemon, whirlwind to prevent stuff from setting up, and roost to temporarily remove three of its weaknesses. Replace Mewtwo's shadow ball and aura sphere with calm mind to raise special attack, ice beam to cover dragon, flying, and ground, and fire blast to cover bug and steel. The Arceus set you have right now won't work because most Ubers Pokemon can set up and defeat Arceus before perish song activates. Give Arceus a life orb for more power and 4 HP/252 Atk/252 Spe jolly to take advantage of its larger physical movepool. Teach it swords dance to raise physical attack, extreme speed to sweep without having to outspeed, shadow claw to cover ghost, and earthquake to cover rock and steel.