Sylveon is the only Eeveelution that hasn't appeared in Pokemon GO yet, and players have been waiting to see it since the release of the Kalos region. That wait might be over very soon though based on some new information.
Unfortunately, Sylveon is not available to catch or evolve in Pokemon GO; at least not yet. When Kalos region released, there was a guarantee that the Fairy-type Eeveelution would eventually make an appearance. But for a couple of weeks now, many players have come to the conclusion that Sylveon is set to release in the very near future.
Aside from Kalos region releasing, a new load screen in Pokemon GO is what sparked the conversation about Sylveon. Some eagle-eyed players spotted what looks like Sylveon in the background of the most recent load screen added to the game, which is heavily Spring-based. However, the Sylveon evolution name has created even more excitement.
The Sylveon evolution name gets revealed in Pokemon GO
Recently, players discovered that the name for the Sylveon evolution may possibly be "Kira". For some, the outline of Sylveon has appeared when naming their Eevee with Kira specifically.
On top of that, when players attempt to evolve the Eevee into a Sylveon using "Kira", a network error has appeared for some. It seems to be more proof that the final Eeveelution is waiting to be released very soon in Pokemon GO.
That release may even be in April if some theories are to be belives. Friendship Day occurs in Pokemon GO at the end of the month, and many are holding out hope that Sylveon appears then. If so, players can finally complete their full Eevee collections.