Just like in other Pokémon games, Feebas has a special way to evolve into Milotic in Pokémon Go. To evolve Feebas into a Milotic, you'll need to walk 20 kilometers with it set as your buddy. Set the specific Feebas you want to evolve as your buddy in order to evolve it.

Do you need 100 candies to evolve Feebas?

The Buddy Evolutions are uncommon in Pokemon Go, but it is natural because Feebas requires a high “Beauty” condition before it can evolve. You have to walk Feebas as your buddy for 20km and have 100 candy to evolve it to Milotic. ... Feebas is the third one who needs a special treatment before evolving.

How do I evolve Feebas into Milotic sword?

To evolve Feebas into Milotic you need to trade Feebas whilst it is holding a Prism Scale. There's no level requirement, so find a friend and ensure you've got a Pokemon to swap it back for. Set up a Link Trade by entering the same code and swap the Feebas back and forth to acquire your fancy new Milotic.