>>36173571Possible but the Z-move move user is the most important. I can see Hau using Pikachunim-Z and later on getting some devlopment and evolving his pikachu to Riachu and getting the Riachu Z-move. If he had a Decidueye on the sidelines it would probably be the equivalent of Tysion in the Hoenn league with his sceptile that was only there to job.
Also it kinda was a hint. Unless you consider calling a Pokemon by name and showing its evolution while asking "will it evolve?" Right in the middle of the anime. Practically the biggest hint we can get for a Rowlet evolution.