https://www.gamespot.com/articles/pokemon-gos-next-community-day-event-announced/1100-6457022/

The second Pokemon Go Community Day event may have only recently concluded, but Niantic has already revealed details for next month's event. The third Pokemon Go Community Day takes place on March 25, and this time it'll feature one of the original three starting Pokemon from Red and Blue.

Like the previous two Community Days, next month's event is scheduled to run for three hours, beginning at 11 AM PT / 2 PM ET and ending at 2 PM PT / 5 PM ET. As before, players will be able to obtain a rare Pokemon that knows a special move it cannot typically learn during the event hours. Niantic hasn't revealed what the exclusive move will be for March's Community Day, but the featured Pokemon will be the Grass-type starter Bulbasaur.