There’s always a chance you can encounter a shiny Pokémon in Pokémon Go, a different version of the original one. It comes with a unique color palette that makes it stand out from the others, and it also has a distinct shine when you summon it into a battle. Many trainers are looking for the chance to potentially capture a legendary shiny Pokémon, which is even rarer than the regular shinies because of how few chances you have to catch a legendary. You can only find them in five-star raids, as rewards for competition in the Pokémon Go Battle League, or in special research projects. For those eager to catch a shiny Therian Forme Thundurus, you won’t be able to do that this time around, but you can check it out in your Pokédex if you captured a shiny Incarnate Forme. While it is different than the Incarnate Forme, and has a unique moveset, the Therian Forme Thundurus does have a shiny version.
Whenever a new Pokémon debuts to Pokémon Go, Niantic typically has the shiny assets added to the game. They’re available in the backend, but they don’t always make those assets live, which means a shiny Pokémon’s appearance can be ready to go, but players have no chance of encountering it.
A Pokémon’s shiny version usually comes out during a special event following its release. These vary from several months to a year later. For example, before Therian Forme Thundurus’ release on March 16, the three Forces of Nature legendary Pokémon, Tornadus, Thundurus, and Landorus, had their shiny versions released for the first time. When the trio were originally released a year ago in 2020, they did not have any shiny versions available for players to catch when available. You can have a sneak peek at the Pokémon, but when you encounter it at five-star raids, it will be in its regular form. There won’t be a chance for any shiny versions to appear.
You can’t capture a shiny Therian Forme Thundurus at this time. It typically doesn’t work that way when a new Pokémon releases.