Niantic have announced the details for the 15th Pokémon GO Community Day which takes place on April 13th, 2019 at 3:00 PM until 6:00 PM EST. The featured Pokémon for this day is Bagon. Bagon will appear in the wild more frequently for three hours that day. If you evolve Shelgon into Salamence during the three hour window, your Salamence will know the move Outrage. The 3x Catch XP and 3-hour Lures bonuses will also be available that day.

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