Pokémon Go ‘Evolving Stars,’ Collection Challenge event guide
Pokémon Go’s “Evolving Stars” event has a Collection Challenge that requires you to evolve Eevee, Haunter, and others. Our guide lists the Pokémon and rewards.
This article references relevant content from the polygon.com website. Original article link: [https://www.polygon.com/pokemon-go-guide/23389250/evolving-stars-collection-challenge-evolve-eevee-event]

The latest Pokémon Go event, “Evolving Stars,” runs from Oct. 5-11 and features Pokémon who evolve using items and trades. The event features multiple Collection Challenges, special Field Research, and special spawns.
Notably, the event also adds a few more tasks to the Cosmog Special Research, “A Cosmic Companion.”
Below, we list out all the “Evolving Stars” Collection Challenges, spawns, Field Research, and raid targets.
Evolving Stars Collection Challenges
Unless you’re going for Collection Challenge medals or you need the evolution item rewards below, these challenges are probably not worth the stress. It can serve as a nice reward if you don’t have some of these evolutions already, but I would not stress over evolving Eevee into the correct evolution just to get these items.
Eevee’s three evolutions — Vaporeon, Jolteon, and Flareon — are completely random, assuming that you’ve used the naming trick to get each one guaranteed once.
Rewards: 1 Upgrade, 1 Metal Coat
Rewards: 1 Dragon Scale, 1 Sun Stone, 1 Kings Rock
Rewards: 2 Unova Stones
Rewards: 2 Sinnoh Stones