SM Ubers Rate my Uber team pls

[GANGTEAMSALLY]

Arceus @ Aguav Berry
Ability: Multitype
EVs: 252 HP / 252 Atk / 4 SpD
Adamant Nature
- Extreme Speed
- Swords Dance
- Recover
- Shadow Claw

So I usually start the game out with Arceus, so I can try to swords dance Extreme speed sweep early on. If they have a ghost type, you can shadow claw that. I went with the bulky set, so it can tank for a few attacks while getting off some swords dances. If arceus starts getting to low HP, recover can annoy your opponent if you just spam it. The only counter to arceus that I can think of at the moment is Close Combat on Marshadow.

Groudon-Primal @ Red Orb
Ability: Desolate Land
EVs: 252 Atk / 4 SpA / 252 Spe
Naive Nature
- Earthquake
- Fire Punch
- Stone Edge
- Swords Dance

Groudon is also tanky, but every team needs a earthquaker. We put fire punch on it because it is an attacker, and stone edge helps keep fire types (especially Charizard) in check. Groudon is pretty fast, so it should be able to get off a swords dance. A lot of other teams have Primal Groudon as well, which is the only decently effective counter to Groudon.

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

Marshadow is fast, a good attacker, and immune to normal type priority attacks. I ran shadow sneak in case the other pokemon had a sash, or just to get a little bit of damage off with the technician. Ice Punch helps KO dragon types, and spectral theif is marshadows signature ghost type attack, and it also steals the stat boosts of a sweeper. Close Combat seemed like a good option to run because it is fast.

Lugia @ Leftovers
Ability: Pressure
EVs: 252 HP / 4 SpA / 252 Spe
Timid Nature
IVs: 0 Atk
- Toxic
- Roost
- Aeroblast
- Calm Mind

If there are any tanks on the other team, I will toxic roost it out with lugia. I put Aeroblast as a balancing move, but Lugia is more of a staller than a attacker. Once Lugia gets off 2-3 calm minds, it basically becomes the ultimate tank and is very annoying with roost. Yveltal and Darkrai would take it out,but it should tank for one of their moves and then it can get off a toxic.

Yveltal @ Leftovers
Ability: Dark Aura
EVs: 248 HP / 8 SpA / 252 SpD
Calm Nature
- Foul Play
- Oblivion Wing
- Roost
- Sucker Punch

Yveltal keeps fighting and ghost types in check, and Sucker Punch is a good priority move if a sweeper on the other team is down to a little bit of their health. Since Yveltal is a tank, we decided to run Roost on it. Ice Punch or ice type attacks is Yveltals greatest weakness, but it can tank for it. Its special attack is really good, so it can also delete psychic types.


Xerneas @ Power Herb
Ability: Fairy Aura
EVs: 248 HP / 8 Atk / 252 SpA
Mild Nature
IVs: 0 Atk
- Geomancy
- Focus Blast
- Moonblast
- Thunderbolt

My secondary sweeper is Xerneas, with the Geomancy Power Herb. Moonblast can sweep with the boost from Fairy Aura after the Geomancy, and thunderbolt can take out a Kyogre while its rain boosts it. Steel types are taken out by Focus Blast, so that means its main weakness is from Poison types. If it gets off the Geomancy, its usually game over for your opponent.,

 

[plant based]

I usually run Fairium Z on Xerneas for the extra sweep help with Geomancy as it helps tank an additional hit, and you dont't have a z-move on here so it should be a nice addition. Other than that, this team looks pretty solid to me.

 

[737373elj]

I usually run Fairium Z on Xerneas for the extra sweep help with Geomancy as it helps tank an additional hit, and you dont't have a z-move on here so it should be a nice addition. Other than that, this team looks pretty solid to me.

But I usually run Power Herb and that’s good for Geomancy as it only then takes one turn

 

[plant based]

But I usually run Power Herb and that’s good for Geomancy as it only then takes one turn

Both work very well, it's usually just personal preference. I was suggesting my preferred alternative.

 

[Ronneberg]

Turbo-Killer Arceus is always a nice threat to dispatch teams that aren't prepared for them, I recommend only changing the item on it to either a Life Orb to make sure E-Speed kills non-defensive Yveltal or Chople Berry to help with the fighting type weakness you already mentioned. Also I would not lead off with Arceus since that tends to do best as a mid- to late-game sweeper, it also gets stopped in its tracks by dedicated leads such as Deoxys-Speed which can taunt it turn 1 preventing it from setting up with SD and get hazards on the field after that, or Smeargle who can Nuzzle it to make it easier to kill. Shadow Claw is a viable coverage move, but Earthquake can really help with Primal Groudon.
I don't know what you need the SpAtk investment on the Primal Groudon for, but a Jolly nature with maximum investment in Atk and Sp should do the job best for you right now, the moves are ok, you could also swap up Stone Edge for Rock Tomb to help support other members of the team, it also prevents you from being swept by Mega Salamence, which could, if played correctly, tear huge chunks out of your team. Just on a sidenote, there are a lot more checks and counters to Primal Groudon, i.e. Giratina Origin or Groundium Z Dugtrio.
I have absolutely no problem with your Marshadow, Marshadow is a supreme offensive presence. Since you're running a sash-set, try considering Endeavor.
Your Lugia will get absolutely minced by Ferrothorn or Arceus Steel running Toxic. You have no Toxic switch-in and your team lacks a Heal Bell/Aromatherapy user, making it only good against offensive stallers like some Mewtwo X builds or several Calm Mind boosting Arceus's. Magearna with Heart Swap is going to turn that Calm Mind boost completely against you and initiate a counter-sweep. You have some checks to that on your team though.
Defensive Yveltal is a useful set to run, but because you don't have a Defog/Rapid Spin user on your team that longevity isn't going to benefit you for long.
Your Xerneas is the set everybody wants the enemy to run, because it is heavily flawed. First of all, a Mild nature and 8 Atk IV's? What's that for. Power Herb Geomancy is a supreme threat in Ubers, but your set gets completely creamed by Heart Swap Magearna, Ferrothorn, or Aegislash (the main counters to Geomancy Xern). Hidden Power Fire is mandatory on Geomancy Xern because of these counters. I'd also swap Thunderbolt for Thunder, which can't miss in Kyogre's Rain.

Overall I'd say that your team is ok, but a thoroughly well built team wielded by a good player will get rid of it with ease.