Legendary Pokémon Raikou will no longer be a Research Breakthrough reward from September 1 in Pokémon GO

For the current month of August 2018, Field Research tasks focus mainly on Electric-type Pokémon in Pokémon GO. If you collect enough stamps to make a Research Breakthrough, you’ll get the opportunity to catch the Legendary Pokémon Raikou. Like all Legendary Pokémon, you won’t find Raikou loose anywhere in the wild, so don’t miss this chance to catch it. Don’t forget to work toward a Research Breakthrough before the Electric-type Legendary Pokémon Raikou goes away on September 1.

Source: @PokemonGoApp