- after you have beaten the game go to mauville city, in the poke center area, go to the south of the tower in the middle, watson should be waiting there, talk to him
- he will give you access to mauville hills, search around until you come across a guy yelling into an apartment, get through the cut scene.
- either go out of the area and come back or do watson’s request, he should be outside that same apartment
-talk to him and voila! Lopunnite
hope this helped! you’re welcome :D