To evolve Eevee into Sylveon in Pokémon Go, you can use the nickname "Kira". Once you have renamed your Eevee to "Kira," you should see a silhouette of Sylveon underneath the standard "evolve" button. Its important to note that this naming trick only works once per evolution type, so choose your Eevee wisely before evolving it into Sylveon.