Despite being a short route, Route 9 serves as an intersection between many different locations, most notable of which is Konikoni City to the west. Outside the exit from Diglett's Tunnel lies the Route 9 Police Station, with one of the resident Police Officers standing outside the station and being ready to battle the player. The south end of the route contains a small bit of coastline, allowing the player to fish.
The Ditto Five
In Pokémon Ultra Sun and Ultra Moon, if the player interacts with the Police Officer in the rear of the station, they will discover he is a Ditto in disguise, and battle it. After capturing or defeating it, the officer behind the desk will say that the Ditto was a member of the Ditto Five and will ask that the player help him apprehend the rest. As thanks for the first Ditto, he will award the player with 12,000.
The remaining Ditto are hidden somewhere in Konikoni City. The player will encounter them in sequential order, and will need to collect their reward in order for the next one to spawn. Each Ditto always has a set Nature and IVs that complement them. After apprehending all five, the policeman will give the player a Focus Band.