Special evolves are always a pain. You just have to keep in mind that Pokemon only evolve when they feel ready, whether if they want to be stronger or even more beautiful; just look at Feebas. This video will show you exactly how to evolve Feebas to a Milotic in Pokemon Ruby, Sapphire, and Emerald.
This is a guide to evolve Feebas on Pokemon Ruby, Sapphire and Emerald. First you have to beat the Elite Four. Then go to "Berry Master's House" in route 123. Talk to the Berry master's wife. Tell her "Challenge Contest", and she will give you Pamtre Berry. Plant the Pamtre Berry, until you have about 5 of them. (It takes 3 days to grow) You can also clone them on Pokemon Emerald: www.youtube.com Then go and Berry Blend with the berries. Give the Pokeblocks to Feebas, so it gets max beauty. Give Feebas one level and it will evolve to Milotic.