The Legendary Pokémon Ho-Oh has returned to Pokémon GO. The iconic Rainbow Pokémon and its rare Shiny form are now available in Raid Battles until August 27 at 20:00 UTC, to coincide with the ongoing Johto Week festival. The official announcement from the development team at Niantic is as follows:
Attention, Trainers! For a limited time until August 27, the Legendary Pokémon Ho-Oh is returning to Raid Battles. This will be your chance to end Johto Week with a surprise, as you just might encounter its Shiny form!