This Route has a sizable portion that requires Cut. Find a temporary Pokemon that you can teach it to and bring it for the meantime. If you don't have a Pokemon that can learn Cut, (don't teach it to your main party Pokemon) you can catch a Nincada in this route.
The path will split to the north and south. To the north, you'll find a Potion near the ledge. There's also a trainer nearby. To the south you'll find a Repel, and another trainer.
Youngster Joey (Prize Money: P144)
Bug Catcher Jose (Prize Money: P112)
Continue further to the east and you'll encounter two more trainers along the way.
Lass Janice (Prize Money: P160)
Hiker Clark (Prize Money: P320)
You'll find the Tunneler's Rest House to the north but you can't go in right now. Before heading further east, go the woods to the left first and use Cut on the bush. This will give you access to two trainers. You can navigate away from their line of sight but that won't be beneficial to you. Head further to left while cutting down thorns to find an Ether and harvest x6 Chesto Berries.
School Kid Jerry (Prize Money: P200)
School Kid Karen (Prize Money: P160)
Proceed to the east this time. Before entering the tunnel, climb the stairs on the mountainside to get an X Sp. Atk. There's also a spot on the right side of the second stairs to the north where a Secret Base is located. You can't do anything about it for now but take note its location. Outside the tunnel entrance, you'll find Mr. Briney and he'll whine about a thug that stole his Peeko. When ready, enter the tunnel.