Rate my Uber team

Question

Groudon @ Red Orb
Ability: Drought
EVs: 252 HP / 56 Def / 200 SpD
Relaxed Nature
- Stealth Rock
- Precipice Blades
- Lava Plume
- Dragon Tail

Xerneas @ Power Herb
Ability: Fairy Aura
EVs: 184 HP / 28 Def / 252 SpA / 44 Spe
Modest Nature
IVs: 0 Atk
- Geomancy
- Moonblast
- Hidden Power [Rock]
- Thunder

Salamence @ Salamencite
Ability: Intimidate
Happiness: 0
EVs: 80 HP / 252 Atk / 176 Spe
Adamant Nature
- Dragon Dance
- Frustration
- Dragon Claw
- Earthquake

Deoxys-Attack @ Focus Sash
Ability: Pressure
Happiness: 0
EVs: 68 Atk / 252 SpA / 188 Spe
Naive Nature
- Psycho Boost
- Superpower
- Knock Off
- Extreme Speed

Arceus @ Silk Scarf
Ability: Multitype
Happiness: 0
EVs: 4 HP / 252 Atk / 252 Spe
Jolly Nature
- Extreme Speed
- Swords Dance
- Earthquake
- Shadow Claw

Mewtwo @ Life Orb
Ability: Pressure
Happiness: 0
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Psystrike
- Ice Beam
- Fire Blast
- Poison Jab

Comments

A little feedback from me, but overall, pretty solid team.
-Groudon:
I think you should replace Dragon Tail with Roar, to counter other Pherb Xerneas'
-Xerneas:
Good set, maybe replace HP-Rock with HP-Ground to get the upperhand against Groudon
-Salamence:
Also, pretty solid set. Maybe you should replace Frustration with Double Edge, but this works as well. Outrage can come in handy too instead of Dragon Claw, but be warned with Fairies switching in and confusion.
-Deoxys-A:
Nothing bad on this to be said. Maybe add Poison Jab for Xerneas and Arceus-Fairy
-Arceus:
Perfect set. But maybe give it a little bit of HP EV's instead of Attack, because Swords Dance already boosts this.
-Mewtwo:
Perfect set. No feedback needed.
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Replace Groudon's dragon tail with roar to hit fairies and protect users. Replace Salamence's dragon claw with roost to heal itself and get more turns to set up. Replace Mewtwo's poison jab with taunt to prevent stuff like toxic and whirlwind.

Answer 1

First things first, Groudon.

Your Groudon is decent. Good EV spread, Good Moves, But I think you would rather go with Hasty > Relaxed. But still, Entry Hazard Switcher Moves are still stereotypical godly sets.

Xerneas. You see, PowerHerb Xerneas is a great set but, I recommend this set instead:

Xerneas @ Powerherb
Ability: Fairy Aura
EVs: 108 HP / 252 SpA / 148 Spe
Modest Nature
IVs: 0 Atk
- Geomancy
- Moonblast
- Substitute
- Hidden Power [Fire]

M-Salamence so... this is your Mega? It's walled by a Dragonite. Here. This makes a better Mega :

M-Gengar @ Gengarite
Ability: Shadow Tag
EVs: 252 SpA / 4 SpD / 252 Spe
Sassy Nature
IVs: 0 Atk
- Shadow Ball
- Sludge Wave
- Protect
- Focus Blast

A-Deoxys. Perfect. No rating needed.

Arceus Silk Scarf +2 252 Atk Arceus Earthquake vs. 252 HP / 252 Def Shuckle: 87-103 (35.6 - 42.2%) -- guaranteed 3HKO See, even with +2 Atk it's walled by a Shuckle. Also, Arceus has base 120 Spd. It's already fast. You don't need more speed.

Mewtwo @ Life Orb
Ice Beam? The only Ubers threat out there 4x weak to Ice is M-Salamence which is a rare threat. But there's not much Bug type Ubers out there. Replace it with Calm Mind. Psystrike for STAB is good, and keep Poison Jab as it covers threats such as Arceus-Fairy, and Xerneas.

Overall, you have a decent team.

Comments

The hasty nature won't help much on Groudon when it has no speed EVs. How is mega Salamence walled by a Dragonite when it knows dragon claw? The max speed investment on Arceus is pretty much only used for outspeeding other Arceuses. The ice beam on Mewtwo is necessary for covering things like Yveltal, mega Salamence (which is pretty common), Zygarde (which is another Ubers threat 4x weak to ice), origin Giratina, Rayquaza (which is a third Ubers threat 4x weak to ice), and Lugia. Also, how does poison jab cover mega Salamence?