Pokémon GO's official Twitter just announced that Kyogre will appear in raid battles all over the world! There is even a chance that the Kyogre will appear in it's shiny form.
Kyogre, the Water-type Legendary Pokémon said to have widened the seas and battled Groudon, has arrived with a splash in Raid Battles around the world. If you’re lucky, you may even encounter a Shiny Kyogre!
- Pokémon GO's tweet