Is this a good Ubers team?

Question

Marshadow @ Focus Sash
Ability: Technician
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Close Combat
- Spectral Thief
- Ice Punch
- Fire Punch

Shaymin-Sky @ Life Orb
Ability: Serene Grace
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Air Slash
- Seed Flare
- Earth Power
- Grass Knot

Yveltal @ Big Root
Ability: Dark Aura
Shiny: Yes
EVs: 252 HP / 252 SpA / 4 SpD
Modest Nature
IVs: 0 Atk
- Oblivion Wing
- Heat Wave
- Focus Blast
- Dark Pulse

Zekrom @ Choice Scarf
Ability: Teravolt
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Fusion Bolt
- Dragon Claw
- Crunch
- Rock Slide

Arceus @ Leftovers
Ability: Multitype
Shiny: Yes
EVs: 252 HP / 4 SpA / 252 Spe
Timid Nature
IVs: 0 Atk
- Defog
- Earth Power
- Judgment
- Shadow Ball

Aegislash @ Ghostium Z
Ability: Stance Change
EVs: 252 HP / 252 Atk / 4 Def
Brave Nature
IVs: 0 Spe
- Shadow Sneak
- Sacred Sword
- Shadow Claw
- King's Shield

Comments

Replace Shaymin and Zekrom with Rayquaza and Zygarde because they do mostly the same stuff but better. Give Marshadow a life orb to make it hit harder. Fighting and ghost already provide neutral coverage, so replace fire punch with shadow sneak for priority. Replace Yveltal's focus blast with sucker punch for priority. Give it a life orb and 4 Atk/252 SpA/252 Spe hasty to make it faster and more powerful. Replace Arceus's shadow ball and earth power with recover to heal and ice beam for better coverage. Give it an earth plate for more resistances and ground judgement, and give it 252 HP/60 SpA/196 Spe timid to outspeed mega Lucario. Replace Aegislash's sacred sword and shadow claw with toxic to defeat defensive opponents and gyro ball for a more powerful STAB. Give it leftovers and 252 HP/4 Atk/252 SpD sassy for more bulk.

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Thx(12 characters)