In celebration fo Pokemon GO Fest events, Niantic has announced that Pokemon GO players will be able to encounter and catch a Shiny Poliwag starting on Tuesday, August 6 at 10:00 AM (JST).
That being said, players who managed to catch the Shiny Poliwag next day will have the chance to evolve them into a Shiny Poliwhirl, Poliwrath, and Politoed. Shiny Poliwag will be available worldwide but it is tied with the upcoming Pokemon GO Fest 2019 in Yokohama, Japan.
— Pokémon GO (@PokemonGoApp) August 4, 2019
If you’re in Japan where the event will be taking place, expect to see new Special Research Task and on-site challenges that may be similar to the previous Pokemon GO Fest in Chicago and Dortmund.