Pokémon GO recently implemented a brand-new research feature that encourages players to explore the world by completing a variety of objectives with the opportunity to earn helpful rewards and discover powerful and rare Pokémon, including Legendary Pokémon and even Mythical Pokémon. For the very first time, players of the immensely-popular mobile game can now discover the Mythical Pokémon Mew with Special Research! There are three major steps to finding Mew in Pokémon GO – Get the Briefing from Professor Willow, Complete the Tasks and finally Find Mew. Until April 2, completing Field Research and Special Research tasks will reward double Stardust as part of the Pokémon GO Eggstravaganza event.
Trainers, we hope you’re enjoying the new research feature! As a reminder, the Pokémon GO Eggstravaganza event is currently active, so completing Field Research and Special Research tasks will reward double Stardust. While you will see boosted numbers for the next few days, Stardust earned for completing a research task will return to normal on April 2, when the Pokémon GO Eggstravaganza ends. Good luck in your research!
Source: Niantic Support @NianticHelp