Feebas is one of the more elusive Pokémon within Pokémon Brilliant Diamond & Shining Pearl. Keeping its method of obtaining from the original games, Feebas is located within the basement of Mt. Coronet, accessed through Route 211.

While it is found in the basement, Feebas isn't found in the general encounter pool but is instead found in 4 different tiles at random when fishing. These tiles will change each day and you can also find the other Pokémon in the tiles

There is a way to get around it. If a friend has found Feebas' tile and you Mix Records with them in the Union Room, then you will share the 4 tiles for the rest of the day.

Feebas in Mt. Coronet