Courts will typically not transfer a case from one jurisdiction (state) to another unless an action has been filed in the new state. I would therefore not recommend that you attempt to transfer the case to Arizona until you need to modify or enforce the WA order.
Be aware that Washington could retain jurisdiction over its original custody order if the other parent remains in Washington. Please see the attached link to the relevant statute.
Once you feel it necessary to modify the custody/parenting time orders, you will need to register an exemplified copy of the WA order with the Arizona court, along with the required legal documents to get it registered. You will likely need legal assistance with these documents. You may then file a petition to modify at the same time you file to register the WA order.
An additional factor is whether or not the other parent continues to reside in the state of Washington. If the other parent has moved from Washington, then an Arizona court should accept jurisdiction under the facts as stated. You will still need to follow the procedures set out in prior answer to your question.
Sign up to receive a 3-part series of useful information and advice about child custody law.