6th Gen What to do in post story?

Hey guys!! Just finished the game about a day ago, I caught mewtwo, caught zygarde and just did friend safari. What else is there to do? side missions? easter eggs? secrets? and how do you do them? thanks guys and be sure to add my FC in my sig, then pm me ;)

You could do Looker side story it pretty fun if u haven't done it yet.

Redo the Elite 4, Battle Masion, Looker sidequest, Upgrade Mega ring or w.. Shiny hunt, Complete your pokedex, Competitive battle... (I haven't played the game yet but these are the most common things I see)

Egg breeding and online battle is what I do. Also shiny hunting.

Pokemon Like Mewtwo.
Friend Safari.
Roaming Pokemons.
Speacial Places!

I plan on first completing the Pokedex before doing some EV training and then battling online. I still think that there are parts of the game yet to be revealed yet so that will hopefully keep everyone busy!