in the r/s/e/fr/lg pokedex on serrebii.net you can for wich pokemon you have to fish and surf. i know that you have to fish for feebas, staryu, wailmer and magicarp. i also think that the only way to get carvanna and sharpedo is to fish as wel, but i'm not sure. the other pokemon (again not 100%sure) can be found by surfing.