Does it learn Thousand Arrows/Thousand Waves in this game or not?
I mean Zygarde-Complete and Zygarde-10% is gen 7, and they’re in this game
I am almost certain it still uses the Gen 6 learnset. If so, then no. Also, yes, 10% and complete form are in this game but I’m positive you can’t get them for yourself.
My guess is they’ll end up being Move Tutors along with Core Enforcer.
do you know where?
I’m pretty sure there is no tutor for that.
I know there isn’t. That’s my prediction for if they ever DO get implemented into the game. 
How i wish they included his complete form, zygarde is just a poor mans garchomp without his 100% form