Question: are z crystals one time use?
Answer: A Z-Crystal (Zクリスタル Z-Kurisutaru) is a special type of crystal introduced in Generation VII, used to activate a Z-Move. It helps Pokémon use the corresponding Z-Move when equipped with one, as long as it knows a move of the same type. One Z-Crystal can be used as many times and on many Pokémon as one wishes.