Niantic has announced a new Pokemon Go Halloween event focusing on Dark and Ghost-type Pokemon.
Starting today at 1:00PM Pacific Time and running until November 1, the event will increase spawns of Ghost and Dark-type Pokemon including new Generation 4 introductions like Drifloon and Stunky (including the possibility of a shiny Drifloon).
New Special Research will introduce Sinnoh Pokemon Spiritomb, and Legendary Pokemon Giratina will be available to battle and capture in Legendary raids starting today and remaining until November 20.
Source: IGN.com Pokemon Go Halloween Event Announced with New Ghosts