After you make it past trainers and pokémon in Route 6, you reach Stow-on-Side.
Go north from the sign next to the Pokémon Center to find a Dusk Stone behind the building.
There is someone in the Pokémon Center that you can talk to who will give you two Fossilized Birds (Sword) or two Fossilized Drakes (Shield).
West of the Pokémon Center, there is a Bargain Shop where you can purchase one rare item a day, and you can ask what will be available the next day.
To the left, you can sell one treasure per day (such as mushrooms and star pieces) at a higher sell price than usual.
Go west from there and look in the corner to find a sparkle. Check on it to get 2 X Sp. Atks.
Go south from there to find a ladder, then go down the next ladder. Go east from there and check on the sparkle to get 3 Rare Bones.
Go up the ladder near where the sparkle was, and you will find a Rocky Helmet.
Go west down the ledge, then up the ladder. From there, go west and you can go behind the buildings. Go north and up the ladder, then go east and up the ladder there. Go east down the ramp. Talk to the person there, and you can trade a Maractus to get Romeo's Hatenna, named Fringe.
Check on the sparkle north of Romeo to find a Metal Coat.
Go west to jump down the ledge, then go west to find TM74 Venoshock.
Go south to jump down the ledge, then go southwest and down the ladder. Go south, then east to reach the plaza, then go north and approach Hop. He will challenge you to a battle.
Hop has a level 29 Cramorant, a level 33 starter pokémon (if you chose Scorbunny, he has Thwackey. If you chose Grookey, he has Drizzile. If you chose Sobble, he has Raboot), a level 29 Toxel, and a level 30 Silicobra. You get 2640 Pokédollars for winning.
Afterward, if you are playing Pokémon Sword, you get Bea's League Card, or if you are playing Pokémon Shield, you get Allister's League Card.
Go west from the base of the stairs and enter the house there, and talk to the person to get TM06 Fly.
As you go up the stairs, you will see a ladder on the right. Go up the ladder and go east to find a Cracked Pot.
Go east to jump down the ledge, then go south to jump down the ledges. You will end up next to the Pokémon Center.
Go west, then north up the stairs where you battled Hop. You will find the Stow-on-Side Stadium.