Pokémon Go’s New Year 2021 event features a variety of new costumed Pokémon for you to capture. Players can also look forward to a Ho-Oh encounter to kick off the year happening on Friday, starting at 1 PM PST, but there are additional Pokémon featured in this event, such as a Slowbro with 2021 glasses. You won’t be able to capture it by encountering it in the wild, or by having it appear from a field research task.
The only way to add Slowbro with the 2021 glasses is to evolve a Slowpoke who has the 2020 glasses. This Pokémon is a bit easier to find. You’ll be able to encounter a Slowpoke with this appearance when the event kicks off, and they randomly spawn in the wild, from completing field research tasks, and can potentially hatch from two-kilometer eggs. Once you have a Slowpoke wearing those glasses, you need to receive 50 Slowpoke candies to evolve that specific one, and it will turn into a Slowbro with the 2021 glasses on its face.
Because it’s the evolved form, you’ll be able to power it up as much as possible and use it in the game as much as you like. For the better part of a year, Niantic has been getting better about having costumed Pokémon from events carry over their stats and be used at the highest level, such as a Gengar from Halloween or Raichus with party hats. It could hint that more event-specific Pokémon will evolve, but we won’t know until more events happen in 2021.
Slowbro is a decent Pokémon as a Water and Psychic-type. Unfortunately, it’s not the best Pokémon to use in PvP, so you might only capture it to fill your PokéDex.