okay just got to clarify this better >.> as long as the z move is your type of your gym type then it be fine so for me...So basically, we can use other Z Power type Status moves, like Z-Sandstorm. But not the actual Rock Z-Move.
Twinkle Tackle,and gaurdian of Alola is fine(if the guardians are not in Ubers of course) because they both are fairy type z moves however I can use the Primarina special z move if I wanted but I will not be able to attach the other z power to another pokemon of choice. so basically you can only have one z power attached to your pokemon of choice which can be that pokemons special z move or type z move of your gym. I hope this makes sense XD I am really bad at explaining...I want to try to match the z moves to the type of your gym which is sorta like when we challenged the kahunas in the game they used the type of there pokemons.