Question: where are all z crystals?
Answer: Buginium Z. In Guzma's room in the Shady House in Po Town (Ula'ula Island), in the chest next to the chair.
Darkinium Z. From Kahuna Nanu after defeating him in his grand trial in Malie City (Ula'ula Island).
Dragonium Z. ... 
Electrium Z. ... 
Fairium Z. ... 
Fightinium Z. ... 
Firium Z. ... 
Flyinium Z.