Pokémon Go Unova Celebration event guide: Field Research and rewards - Polygon

From Jan. 5 until Jan. 10, Pokémon Go is hosting an Unova event that increases the spawn rate of the Pokémon from that region, as well as introducing Shiny Snivy.

Unova Celebration Event

Pokémon Go - Wikipedia

Cavalier Langdon Walhalla Area Pokemon Go

Massively on the Go: The Pokemon Go outlook for November 2022

Cavalier Langdon Walhalla Area Pokemon Go

Pokémon Go Sinnoh Celebration Event guide: Field Research and rewards - Polygon

Unova Celebration Special Service - Pokemon GO Account Service

How to easily fix 'Unable to Authenticate' issue in Pokemon Go - Dexerto

Pokémon GO Fest 2019 Dortmund, Pokémon GO Wiki