Quote Originally Posted by Shine View Post
^
if the ability won't matter to you then no, it isn't rare. You can fish for Feebas in Route 1, and with a high encounter chance too, if you fish on a water ripple.
It's hard to get, but not as rare as previous gens. I found one in the Dream World, didn't take it home because I met another pokemon that I wanted more, and I already had one in-game. I got lucky, I got in within 10 minutes of regular fishing.