the first time i shfflc'd i did not even know I was shufflc'ing. I was fighting a trio of lvl.9 bowsers as fox, and jumped through them with a nair (sh), and then ff and hit the ground. What baffled me, even months afterwards, was that sometimes I was able to sh another nair hit them before they can retaliate. I was l-cancelling, and I did not even now it. Coincidently, several months later I came across this site.
I still play Fox sometimes, but I am a ganon main right now, with a little martha on the side.
Its generally harder to shufflc' with little charactors (like fox), then the bigger charactors(booser and ganondorf).
IMO, learning to shufflc with Fox should make it easier to shufflc easier with other charactors, simply because his shfflc is the hardest to do.