Okay, it actually depends on the order of the pokemon being sent out. If your opponent had Groudon and you had Kyogre, I think their Groudon would have the battle with their Drought. I THINK, not too sure.
Kyogre would be good with: Calm Mind, Surf, Ice Beam, Thunder.
Groudon would be [okay] with: Sword Dance, Earthquake, Rock Slide, Hidden Power (bug).
With Kyogre's moveset, he can take out Groudon with Ice Beam even if Groudon's effect is applied.
With Groudon's moveset, his best bet is probably Hidden Power (bug) because HP grass would be counted as a special attack. I'd go with Rock Slide/Earthquake, though.
Meh, Kyogre pwns Groudon any time, any day.
Until a day comes where someone can PROVE ME WRONG
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