After discovering a Snorlax sleeping on the Route 6 bridge, Shauna says to take Palais Lane to reach Parfum Palace.
You may encounter wild Venipede or Audino if you go close to the large bushes on either side of the path.
When you enter Palais Lane, you see a tree-lined path down the middle. If you talk to the backpacker, he says that there is an easy way and a difficult way through Palais Lane, and you'll take the difficult way on your way back.
Go west from the backpacker along a narrow path south of the tall grass. You'll find an X Sp. Atk.
Go north along the path between the trees. You'll encounter Tourist Hiroko. She has a level 11 Pikachu, a level 11 Pidgey, and a level 11 Psyduck.
North of the first tourist, you encounter Tourist Eriko, who has a level 11 Zigzagoon, a level 11 Ralts, and a level 11 Gulpin.
After this, just walk north to reach Parfum Palace.