This route usually has a light mist covering, but occasionally, the mist on this route and Route 14 will disappear.
From Black CityBB2/White ForestWW2 Route 15 leads westwards up some stairs, then across a bridge to the Poké Transfer Lab. Past the Poké Transfer Lab there is another bridge and more stairs heading south. West of these stairs there is a trailer where Lillian will offer to trade her Rotom for a Ditto.
Alternatively players can head down some stairs south of the eastern gate and through tall grass. There are two Strength boulders in this route, the south eastern one leads to an item while the northern one leads to dark grass and another item. Continuing east past the Strength boulders there is more tall grass and a narrow path up some stairs leading to a hidden item. There are three ledges in the western half of this route. One runs horizontally and must be jumped over from the north for players to continue westward through this part of the route. The other two run vertically and are eastbound. A large rock prevents players from avoiding the ledges by travelling between them.