After becoming Primal Groudon, a very Strong Sunlight will take hold. Unlike Drought, the weather is locked into Strong Sunlight and cannot be changed by another Pokémon's moves or Abilities. Additionally, Water-Type moves won't have any effect, evaporating before they reach their target(s), and the weather condition will last until Primal Groudon is removed from battle.
Desolate Land doesn't have an effect in the Overworld.
Pokémon With This Ability