After you get a Pokétch in Jubilife City, you go through Route 203 on your way to Oreburgh City.
Battle Your Friend
As you go east, your friend will challenge you to a battle. He has a level 7 Starly and a level 9 starter pokémon (Chimchar if you picked Turtwig, Piplup if you picked Chimchar, Turtwig if you picked Piplup). You get 1188 Pokédollars for winning.
Feel free to go back into Jubilife City to heal up your pokémon after the battle.
Go Through the Route
In this route, you can catch Abra (but you will need to throw a pokéball right away because it uses Teleport to run away), Bidoof, Kricketot, Shinx, Starly, and (only at night) Zubat.
From where you battled your friend, you can either go north through the tall grass to avoid a trainer battle, or you can go north and battle Youngster Michael, who has a level 5 Bidoof and a level 5 Zubat. You get 380 Pokédollars for winning.
Go east from the Youngster to find a Poké Ball.
Jump down the ledge south of the Poké Ball, then go east. You can either go through the tall grass near the water to avoid the trainer battle, or past the trainer to fight Youngster Dallas. He has a level 7 Kricketot. You get 392 Pokédollars for winning.
Go east up the stairs and you will battle Lass Kaitlin. She has a level 4 Bidoof, a level 4 Starly, and a level 4 Budew. You get 352 Pokédollars for winning.
Go east and you can battle Youngster Sebastian, who has a level 7 Machop. You get 392 Pokédollars for winning.
North of there, you can fight Lass Madeline. She has a level 5 Starly and a level 5 Bidoof. You get 380 Pokédollars for winning.
Go west from the Lass and down the stairs to find a Repel.
Go east from the Lass and enter the cave to reach Oreburgh Gate.