Aren't canonically Groudon and Kyogre supposed to be equal?
The battle kinda uses game mechanics (which yes Pokémon is a game, but in all other media Pokémon battles are not turn based)
Oh, and canonically, when
Groudon and Kyogre fight, their abilities don't cancel each other, but rather create a sort of fused weather that mixes sun and rain
So all around, Kyogre and Groudon should be equal to each other, meaning they cancel each other out, with the rest of Maxie and Archie's team also being equal
This is probably inconclusive