https://www.gamespot.com/articles/pokemon-go-july-community-day-announced-features-s/1100-6459908/

June's Pokemon Go Community Day is now in the rear-view mirror, and developer Niantic has shared the first details on next month's event. July's Community Day is scheduled to take place during the first weekend of the month, on July 8, and features another popular starter Pokemon from the Kanto region: Squirtle.

For the duration of the event, the Water-type starter will appear much more frequently in the wild. Based on previous Community Days, players will presumably also have a chance to encounter a Shiny Squirtle during the event. Any Squirtle that manages to evolve into its final form, Blastoise, before the Community Day ends will learn a special event-exclusive move--although Niantic hasn't revealed what that attack will be just yet.