The best thing about Rick and Morty is that due to the infinite nature of its multiverse, everything you can possibly think about is canon.

Your fanfic about Rick beating up disney characters? canon.

Your headcanon of Morty being into tennis? canon.

A game about Rick collecting Mortys like pokemon across the multiverse? canon.

Everything is canon. Except the Smiths being happy. The Smiths can never be happy in canon.