In 2019, Pokémon GO introduced the concept of Limited Research Days. These are days where, for three hours, a certain event exclusive piece of Field Research will be available for players. This research is then forever with the player. Each region has the event at different times. Click the Limited Research Day for more details

Marill DayMarill Day May 9th 2021 Marill
Sneasel DaySneasel Day January 30th 2021 Sneasel
Nidoran DayNidoran Day November 28th 2020 Nidoran♂
Meowth DayMeowth Day October 10th 2020 Meowth
Snubbull DaySnubbull Day May 9th 2020 Snubbull
Minccino DayMinccino Day February 2nd 2020 Minccino
Weather DayWeather Day March 30th 2018 Lotad
Clamperl DayClamperl Day February 23rd - February 24th 2018 Clamperl
Feebas DayFeebas Day January 19th - January 20th 2018 Feebas