Niantic has announced that from Tuesday, January 5th, 2021, at 10:00 a.m. to Sunday, January 10th, 2021, at 8:00 p.m. local time, Pokémon from the Unova region will show up more often in Pokémon GO.

Countdown to Pokémon GO Tour: Kanto—celebrate the Unova region with us!

Trainers, We hope you enjoyed the Kalos Celebration event a few weeks back! As we count down to Pokémon GO Tour: Kanto, we’ll continue to celebrate the various regions of the Pokémon world—with Unova up next!

Date + Time
Tuesday, January 5, 2021, at 10:00 a.m. to Sunday, January 10, 2021, at 8:00 p.m. local time

Features

• Snivy, Tepig, Oshawott, Lillipup, Herdier, Blitzle, Roggenrola, Drilbur, Scraggy, Tympole, Venipede, Trubbish, Gothita, Solosis, and Ferroseed will be appearing more frequently in the wild! If you’re lucky, you might encounter a Shiny Snivy!
• The following Pokémon will be hatching from 5 km Eggs: Roggenrola, Sewaddle, Petilil, Emolga, Karrablast, Joltik, Elgyem, and Shelmet
• Enjoy event-exclusive Field Research tasks that reward Stardust and lead to encounters with Pokémon such as Snivy, Tepig, Oshawott, and Ferroseed.
• The following Pokémon will be appearing in raids.
  • Snivy, Tepig, Oshawott, Timburr, Dwebble, and Klink will be appearing in one-star raids.
  • Herdier, Tranquill, Excadrill, and Amoonguss will be appearing in three-star raids.
  • Genesect holding a Burn Drive will be appearing in five-star raids. This will be the first time this form of Genesect will be appearing in Pokémon GO, so be sure to catch it while you have the chance! Note that the Shiny form of this Genesect will not be available during this event.
  • Mega Charizard Y, Mega Blastoise, and Mega Abomasnow will be appearing in Mega Raids, with Mega Charizard Y becoming even more powerful from Tuesday, January 5, 2021, at 10:00 a.m. through Tuesday, January 12, 2021 at 10:00 a.m. local time.
• Stay tuned for Collection Challenges, a new feature in the Today View that’ll make Pokémon GO events all the more exciting to experience! More details to come in early January.

Up next: Sinnoh! An event celebrating the Sinnoh region will be happening from Tuesday, January 12, 2021, to Sunday, January 17, 2021. Stay tuned for more details!

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/unova-celebration-event-2021