Niantic has announced that from Wednesday, December 2nd, 2020, at 10:00 a.m. to Tuesday, December 8th, 2020, at 10:00 p.m. local time, Pokémon originally discovered in Kalos—the region will be appearing in the world of Pokémon GO!

Celebrate the arrival of Pokémon originally discovered in Kalos with a special event!

Trainers, Pokémon originally discovered in Kanto, Johto, Hoenn, Sinnoh, Unova, Alola, and Galar have appeared in Pokémon GO. And starting today, Pokémon originally discovered in Kalos—the region where Mega Evolution was first discovered—will also be appearing in the world of Pokémon GO! To celebrate their arrival, you’ll be able to take part in a special event.

Date + Time
Wednesday, December 2, 2020, at 10:00 a.m. to Tuesday, December 8, 2020, at 10:00 p.m. local time

Features

• Chespin, Fennekin, Froakie, Bunnelby, Fletchling, Litleo, and Noibat will be appearing more frequently in the wild! In addition, Klefki will be appearing in the wild only in France. These Pokémon will be appearing in the wild after the event ends.
• The following Pokémon will be hatching from Eggs! They’ll continue to hatch from Eggs after the event concludes.
  • Bunnelby, Fletchling, and Litleo will be hatching from 2 km Eggs.
  • Chespin, Fennekin, and Froakie will be hatching from 5 km Eggs.
  • Espurr and Noibat will be hatching from 10 km Eggs.
• Litleo and Espurr will be appearing in one-star raids.
• Enjoy event-exclusive Field Research and Timed Research tasks that lead to encounters with Pokémon such as Bunnelby and Fletchling as well as reward Venusaur Mega Energy, Charizard Mega Energy, and Blastoise Mega Energy.

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/gobeyond-kalos-launch