Every month in 2020, the Field Research tasks that can be found at PokéStops in Pokémon GO have shifted to the month's theme to match the typing of the Research Breakthrough Pokémon. This month is Ghost-themed due to Halloween, and will also feature, as always with Niantic's October events, Dark-type Pokémon. Here is a breakdown of the new and returning tasks that can be found from spinning these stops, with information about the Pokémon encounters that can be earned through completing these tasks… including some Shiny Pokémon with boosted odds.
Catching Pokémon Tasks
Poké Ball Tasks
Pokémon GO brings no changes to any of these here for this month.
Pokémon Buddy & Friend Tasks
Pokémon GO Raid and PVP Tasks
This one is major, especially for Pokémon GO players who missed out last year. Yamask returns!