It helps to status the pokemon too. Like growl,leer, etc.
I've also noticed some pokes take more effort than others. i.e. rarer pokemon have a harder catch rate, but it could all be luck. Just me two cents/observations!
Shadow Sneak is base 40, but nightshade is broken (not sure what it's set to, wiki doesn't say).
You can always edit moves from playerdex if you want to test them yourself.