Pokémon had always had all sorts of ways to counter one another, from type advantages and Ability immunities to evading moves. These counters did not apply only to ordinary Pokémon; they were practically rules of the world.
Arceus's Plates had special powers. Each Type Plate granted an immunity, and in theory, Arceus could not be harmed by any attack with a complete set of Plates, unless Arceus chose to use its physical body to counter something.
Under the extremely harsh sunlight created by Groudon's Desolate Land, Water-type attacks became ineffective.
Kyogre's Primordial Sea did the exact opposite, preventing Fire-type attacks from taking effect, while Rayquaza's Delta Stream disrupted the weather and eliminated Flying-type weaknesses.
In a sense, both the extremely harsh sunlight and the heavy rain would be neutralized by changes in the upper air currents. With this Ability, Rayquaza was the natural counter to Groudon and Kyogre.
How did one mediate a war between two monsters?
Simple. Beat both of them into submission.
As the battle between Groudon and Kyogre grew ever fiercer, Rayquaza descended from the sky and defeated both sides, forcing the orbs out of Archie and Pikachu respectively. Only after ending the conflict did Rayquaza return to the sky and disappear to parts unknown.
No one could say for sure what had caused all of this or where it had begun. A disaster that could have escalated into a world-ending crisis seemed to have resolved itself through the Pokémon world's own self-regulation.
Rayquaza had no interest in dealing with the people left behind, and there would naturally be others to handle them. Archie and Maxie had realized their mistakes during Kyogre and Groudon's battle, but that did not erase what they had done.
Team Aqua and Team Magma had caused no shortage of trouble lately. The