Niantic has announced the details for the May 2021 Community Day which features the Pokémon Swablu and it will take place on Saturday, May 15th, 2021, from 11:00 a.m. to 5:00 p.m. local time in Pokémon GO.

Swablu features during May Community Day—and Mega Altaria will be appearing afterward!

Trainers, The featured Pokémon for this May’s Community Day will be Swablu, the Cotton Bird Pokémon!

Date + Time
Saturday, May 15, 2021, from 11:00 a.m. to 5:00 p.m. local time

Features

• Swablu will be appearing more frequently in the wild. If you’re lucky, you may encounter a Shiny one!
• Evolve Swablu during the event or up to two hours afterward to get an Altaria that knows the attack Moonblast.
• Take a few snapshots during Community Day for a surprise!
• There’ll be a special one-time-purchase Community Day Box available for 1,280 PokéCoins, featuring 50 Ultra Balls, five Super Incubators, five Incense, and an Elite Fast TM.
• For US$1 (or the equivalent pricing tier in your local currency), you’ll be able to access the Swablu Community Day–exclusive Special Research story, Cotton-Winged Bird.
• Stay tuned for when tickets for the Cotton-Winged Bird Special Research story go live! Tickets are nonrefundable (subject to applicable law and the exceptions set forth in the Terms of Service). Please note that this Special Research will not include an in-game medal.
• Mega Altaria will be making its Pokémon GO debut in Mega Raids at the conclusion of May Community Day on Saturday, May 15, 2021, at 5:00 p.m. local time. This is your chance to collect Mega Altaria Energy to Mega-Evolve any of the Altaria you’ve collected during the event!

Bonuses

• 1/4 Hatch Distance when Eggs are placed in an Incubator during the event period
• Incense activated during the event will last for three hours

Please be aware of your surroundings and follow guidelines from local health authorities when playing Pokémon GO. Upcoming events are subject to change.

Source: https://pokemongolive.com/post/communityday-may21/