i was in a pvp match when both trainers we were left with our milotics with the same moveset (sleep talk-rest-dragon tail-scald).
As you can understand the match goes to whoever finishes his pp last because the other will use struggle and lose faster hp.
When my opponent finished his pp first he did struggle twice and then he wasn't struggle anymore,he wasn't attacking,he was just there letting the turns pass while i was loosing pp and struggle till i lose.
When i asked him later why he wasn't struggling when he lost all his pp he said he was just pressing the sleep talk button and his pokemon didn't struggle anymore.
Well i remember doing that too during our battle and while i had lost all my pp but it wasn't working the same for me.
Well i wanna count that as a bug you should fix and not as a trainers fault ...i don't have a video but please check it if you can.