The official Pokémon website and Niantic have announced that starting on September 30th, 2020, Pokémon GO Trainers can access a Special Research story where they will be able to encounter Victini.

Complete Special Research Featuring Victini in Pokémon GO

On September 30, 2020, Pokémon GO Trainers can access a Special Research story that’ll let them encounter Victini or earn Victini Candy.

On September 30, 2020, Pokémon GO Trainers will have the opportunity to access a new Special Research assignment courtesy of Professor Willow called Investigate a Mysterious Energy. Completing this research will earn Trainers rewards based on whether they accessed certain research during GO Fest 2020.

Pokémon GO Trainers who have accessed July's exclusive GO Fest 2020: Rocket Straight to Victory Special Research will earn Victini Candy for completing this new Special Research. For Trainers who didn't access the GO Fest 2020: Rocket Straight to Victory Special Research, the reward for completing the new Victini Special Research will be an encounter with Victini!

Get ready to research Victini!

Source: https://www.pokemon.com/us/pokemon-news/complete-special-research-featuring-victini-in-pokemon-go/