u will hav to look it up on google like i did, because u need the super rod and u need to fish in the area it says on the pokedex but the problem is he's only on 6 of the 400 squares.
the rarest Pokemon in Ruby Sapphire and Emerald is Feebas
On the Route southwest from Fortree City.
Only in ruby, sapphire and emerald at route 119
Since Feebas is a Water Pokemon,you can only find it in lakes,rivers etc.
THE MOST ANNOYING POKEMON IN THE GAME In the route beetween foretree and mauvile, there is 5 or 3 i cant remember, squares that contain feebas out of 400+!!!!!!!!!!!!
the only way to evolve it is to have the feebas at a high BEAUTY status for Pokemon contests. and the best way to do this is to have a feebas with a MODEST nature.
you can find a feebas in route 118 and 119 but its hard to find
Use a Gameshark
trade it from ruby or sapphire
You must evolve Feebas.
the rarest Pokemon in Ruby Sapphire and Emerald is Feebas
super rod
On the Route southwest from Fortree City.
Saphire Version
Fish with super rod in route 119, BUT it is ultra rare.
Modest is really great!
Super rod is the best rod to use.