Gyarados, Whiscash and Feebas can be caught in the underground lake in Mt. Coronet.
Be warned though that Feebas can only be caught in 4 squares, and the 4 squares are rechosen at random every day.
You can catch Wailmer and Wailord in Route 230, near the fight area.
You can catch Luvdisc and Octillery in the water near Pokemon league (just fly there)
You can catch Corphish, Whiscash, and Crawdaunt in Celestic town in the pond.
You can catch Lumineon, Clamperl on route 219 and 221, Chinchou on route 220, and Octillery and Sharpedo on route 222.
Super rod.
Well You catch Magikarp, Goldeen, Finneon, Psyduck.
You can fish with a super rod
You need to use a super rod
The first trainer (female swimmer) on the way to the Pokemon league (route 223), she has one, Also if you have a super rod you can catch one on route 221
No, try the good rod.
You can catch it in route 225, in the water, but make sure to use good rod not super rod or old rod
With a super rod, you can find them in almost any waters.
Fish for it outside of iron island with a super rod ;)
You could catch a Shellder at Valley Windworks only by using your super rod
1) catch a magicarp with an old rod 2) evolve it. or catch 130 "gyrados" with a super rod at various locations.
a super rod is the best rod in Pokemon pearl/dimond/platnim
You can catch Lanturn in Pokémon Diamond and Pearl by Fishing with the Super Rod in Route 220.
Use a good rod in any of the places it says in the pokedex. To catch an Octilery, use a super rod. (Octilery evolves from Remoraid)
Evolve a Finneon at level 31 or catch it at route 205 with a Super Rod.
you will have to fish for it preferable with a super rod around mossdeep city. you can get the super rod from a man in a house north of mossdeep.
Lumineon is the 135 pokemon, catch a finneon and train it or catch one in route 219 or 220 or canalave city using super rod.