Niantic have announced the details for the 19th Pokémon GO Community Day which takes place on August 3rd, 2019 at 4:00 PM until 7:00 PM EST. The featured Pokémon for this day is Ralts. Ralts will appear in the wild more frequently for three hours that day. During this event, if you evolve a Kirlia into Gardevoir or Gallade, it will know the move Synchronoise, which is exclusive to this event.The 1/4 Egg Hatch Distance and 3-hour Lures bonuses will also be available that day.

Source: https://pokemongolive.com/events/community-day/