Mr.Wiggles

I tried to fish on each and every one of the rocks available to me, but it would just say "Can't use that here." I'm honestly at my wit's end.

I want to use Slowpoke on my team, but I can't fish on route 4 for some reason. I also don't have Rock Climb, so I can't access other water on route 4. Does anybody have a spare slowpoke lying around that they can trade me? Thanks in advance.