Good Team :)
Here are some suggestions:
Groudon Primal
Good set overall, but maybe you should switch Rock tomb for Stone edge. Rock tomb lacks in power and stone edge only misses 20% of the time. Here is my set with full fixes:
Groudon-Primal @ Red orb
Ability: Desolate land
Shiny:Yes
EVs: 152 HP / 236 Atk / 44 SpD / 76 Spe
Adamant Nature
- Stealth Rock
- Precipice Blades
- Fire Punch
-Stone edge
Deoxys-A
Perfect. But choose ice beam over low kick so you can fully invest in SpA :)
Xerneas
Great set! But switch Substitute to Focus blast so Primal Groudon doesn't completely stop you, most people are gonna attack a pokemon sweeping them, so sub isn't the best. Klefki kinda stops you now though. But in return you get coverage for Ferrothorn, Groudon, Dialga, Genesect, Mega Mawile, Bisharp, and more.
Yveltal
Is Sucker punch AND Dark pulse necessary? Switch Dark pulse out for taunt. Taunt DESTROYS Shuckle, Ferrothorn, Forretresse, Chansey, And others. It also links with Sucker punch quite nicely :)
Arceus-Water
Arceus-Water is good,but taking its job a little more difficult, with sets such as Swords Dance Primal Groudon and Double-Edge Mega Salamence rising as common sets due to their increased effectiveness against Arceus-Water. Arceus-Water also has some issues with its moveslots, leaving it unable to perform all its possible roles with just four moves, leading to some team-based moveset choices. Arceus-Water is also vulnerable to entry hazards, status moves, and being trapped by Shadow Tag users, all things that the Ubers metagame has plenty of, which can keep Arceus-Water's effectiveness down. (Sorry I copy-pasted from smogon lol) So yeah. Switch that to Arceus-Normal. Arceus-Normal's lack of weaknesses with an item slot available allow it to be a perfect backup to Deoxys-A and allow it to be a perfect late-game sweeper, this is the set I suggest-
Arceus @ Life orb
Ability:Multitype
EV'S:252 Atk, 252 Spe, 4Hp.
Adamant Nature
-Swords Dance
-Extreme speed
-Dragon claw/Outrage
-Aqua Tail
Outrage can be used over Dragon claw for higher power, but gets forced out by fairy types like Xerneas.
Aqua tail is there to make up for water coverage loss.Recover can be used in this set. But this is supposed to be a sweeper... Extreme speed is a strong prioety move (Sry spelt wrong) That can OHKO Deoxys-A if it's running life orb or nasty plot sweeper.
Solgaleo
Perfect
(Lol these suggestions are trash)