Niantic has announced that a Kanto-themed Raid Day will take place on Sunday, February 28th, 2021, from 11:00 a.m. to 2:00 p.m. local time in Pokémon GO.

Close out the Pokémon Day weekend with a Kanto-themed Raid Day!

Trainers, We’re closing out the Pokémon Day weekend festivities with a Kanto-themed Raid Day! Join us to celebrate some fan-favorite Pokémon as the Season of Celebration comes to an end.

Date + Time
Sunday, February 28, 2021, from 11:00 a.m. to 2:00 p.m. local time

Features

• Articuno, Zapdos, and Moltres will be appearing in five-star raids! If you’re lucky, you might even encounter a Shiny Articuno, Shiny Zapdos, or Shiny Moltres!
• We’re hearing reports that Giovanni will be returning with a different Shadow Legendary Pokémon in his clutches. Get ready to complete some new Team GO Rocket Special Research to save this Pokémon, Trainers!
• Pick up a bundle of three Remote Raid Passes in the shop starting on Saturday, February 27 at 1:00 p.m. Pacific time to Monday, March 1 at 1:00 p.m. Pacific time.
• Earn up to five free Raid Passes by spinning Photo Discs at PokéStops or Gyms during event hours.
• During the event period, you can use a Charged TM to help a Shadow Pokémon forget the Charged Attack Frustration.
• Team GO Rocket Grunts will be appearing more frequently at PokéStops and in balloons throughout the event window.

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/kanto-raid-day-2021/?hl=en