Kyogre

Primal Kyogre is one of the most defining Pokemon in the format thanks to its high stats and ability to provide unabating weather. Primordial Sea offers game-changing team support to almost every Pokemon in the game and turns Primal Kyogre into one of the best answers to Primal Groudon's devastating Fire-type attacks. While Origin Pulse and Water Spout have downsides with regards to accuracy and consistency, respectively, in combination with the damage boost from rain, they grant Primal Kyogre the potential to deal a ridiculous amount of spread damage. When compared to Primal Groudon, Primal Kyogre has no 4x weakness, making it more difficult to eliminate. This is especially true when you take into account Primal Kyogre's extreme bulk, particularly specially, and its wide range of viable EV spreads that are able to patch up the few weaknesses it has. Its physical bulk is not so high that it doesn't fear boosted attacks from the likes of Mega Kangaskhan and Mega Salamence, though. A final word of caution is that should Primal Groudon gain the upper hand in the weather war, Primal Kyogre is often stuck just firing off Ice Beam.