Niantic has announced that starting on February 26th, 2019, players of Pokémon GO will be able to purchase a Team Medallion for 1,000 PokéCoins from the shop which allows allows Trainers to switch teams.

New Team Medallion allows Trainers to switch teams!

Trainers, Taking down Gyms and battling in raids have been a team effort over the last two years. Whether you’re on #TeamInstinct, #TeamMystic, or #TeamValor, you came together with your teammates and helped one another be better Trainers. We’ve loved watching you share your team pride and band together with others to take on new challenges. Are you ready to take your talents to a new team? The team leaders would be excited to recruit you!

We’re happy to share Team Change with you. Later this month, starting at 1:00 p.m. PST on February 26, Team Change will allow Trainers to change teams once per year. Interested Trainers will be able to purchase a Team Medallion for 1,000 PokéCoins from the shop.

Choose your team wisely, Trainers, as you may only purchase a Team Medallion once every 365 days. Once purchased, you can find the Team Medallion in your Bag. When you decide to activate it, you’ll be guided through the team-selection screens to choose your new team.

Any of your Pokémon that are in Gyms when you change teams will be returned with no PokéCoins earned once it’s defeated. You also can’t battle your own Pokémon, so if you return to a Gym one of your Pokémon is defending, your Pokémon will be returned to you with no PokéCoins earned. (You’ll be able to find more information on our Help Center page.)

We can’t wait to see the new Gyms you win with your friends and Pokémon! There’s just one question: Will you be hatching Eggs with Spark, conducting research with Blanche, or battling alongside Candela? Let’s team up and GO!

Source: https://pokemongolive.com/post/teamchange2019