From 1:00 P.M. PDT on September 22 to 1:00 P.M. PDT on October 2, 2017, you’ll earn double Stardust for catching Pokémon and hatching Eggs. Be sure to visit your local PokéStops/Gyms to collect special 2 km Eggs that have the opportunity to hatch Pokémon such as Chansey, Mareep, Larvitar, and more. There will also be special boxes from the in-game shop that feature items like Lucky Eggs, Lure Modules, and all-new Super Incubators which hatch Eggs 1.5 times quicker!
Registering a new Pokémon to your Pokédex will earn you 3XP. Don’t forget that Raikou, Entei, or Suicune will each travel to a new part of the world on September 30, so be sure to catch them while you can!