Actually, if you want to catch a shiny Chinchou, I may be able to help you with that.
So, Normally you put a Pokemon with Suction Cups or something in the first spot of your party right?
Well I found that when my Raichu with Static was first in the party, I didn't break my chain AND I mostly got Chinchous.
However the shiny took forever to appear, and I broke my chain several times, so that's why he was a pain.