Niantic has updated their website with a special treat for players playing Pokémon GO between October 26th and November 1st, 2016:
It’s Halloween season and we have a treat for you! From October 26th to November 1st, you’ll earn double the amount of Candy every time you catch, hatch and transfer Pokémon! Don’t forget your Buddy Pokémon, because they will help you earn Candy four times as fast.
If you encounter more spooky Pokémon than normal, don’t be startled, they want to enjoy the fun too! Scare up some friends, grab your buddy and enjoy this spooky, fun celebration with us!