Run Swords Dance in conjunction with Earthquake over Waterfall to hit Primal Groudon. It gives the added ability to demolish pokes like Aegislash. Assuming Primal Groudon switches into you and nullifies your Delta Stream, you will still be able to hit Primal Groudon without the need to cancel out its Desolate Land with Delta Stream.
"If Delta Stream is suppressed or replaced, the strong winds it causes will disappear. If another Pokémon in battle has the Ability Desolate Land or Primordial Sea, the dominant weather condition will be determined by whichever Ability activated last."
-Quoted from Bulpapedia
Oh and by the way:
+2 252+ Atk Life Orb Mega Rayquaza Earthquake vs. 252 HP / 252+ Def Primal Groudon: 411-484 (101.7 - 119.8%) -- guaranteed OHKO
This is assuming an Adamant Nature. You miss out on this OHKO if you run Jolly, but Im not sure how relevant it is, as most Primal Groudon dont run 252HP/252Def anyways.
This leaves you walled by Skarmory, but it cant do much other than whirlwind you out while taking an enormous amount of damage from Dragon Ascent anyways.
+2 252+ Atk Life Orb Mega Rayquaza Dragon Ascent vs. 252 HP / 252+ Def Skarmory: 203-239 (60.7 - 71.5%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
Oops, I dont think it walls...
