Quoted By:
Kyogre.
Here is the list of Pokemon that are not 2HKO'd by Kyogre at full power (Choice Specs, rain, Water Spout + Thunder + Ice Beam).
Ludicolo
Shedinja
Gastrodon
Seismitoad
Chansey
Giratina
Quagsire
Lanturn
Palkia
Grass Arceus
Ferrothorn/Ferroseed
Even then, this is assuming the Pokemon are as specially bulky as possible and that there are no clandestine cobblestones.
Basically, unless you can quickly damage Kyogre enough to weaken Water Spout, one of your Pokemon is going to die.
