Things You'll Need
Instructions
Give Feebas the "Blue Scarf" item to hold, which raises its beauty stat by 15 points. This bonus only applies while Feebas is holding it.
Speak to Daisy Oak in Pallet Town to get a massage for Feebas, or talk to a Haircut Brother in Goldenrod City Underground to receive a 32-point increase in Feebas' beauty stat.
Take Feebas into battle and fight any Pokémon you come across until Feebas increases in level, causing it to evolve. If you cannot beat any Pokémon with Feebas, simply set her as your top Pokémon and go into a fight, then switch to another of your Pokémon and defeat the opponent; Feebas gets experience from the fight either way. You can also automatically increase a Pokémon's level by feeding it a "Rare Candy."