Kyogre is appearing in Raid Battles in Pokémon GO around the world from January 12th, 2018 until February 14th, 2018 at 1:00 P.M. PST.

Kyogre Appearing in Raid Battles around the World!

Trainers, Kyogre, the Water-type Legendary Pokémon originally discovered in the Hoenn region, is now appearing in Raid Battles around the world! Keep an eye out for Kyogre at Gyms near you, and you may be one of the first to catch this Legendary Pokémon. But don’t delay—Kyogre will only be available until 1:00 P.M. PST on February 14, 2018. Good luck, Trainers!

Source: https://pokemongo.nianticlabs.com/en/post/legendary-kyogre