After you meet Raihan and visit the Vault with Sonia, you go west to Route 6.
Explore Route 6
Go west across the bridge and there will be a cutscene, and you will need to battle Team Yell. The Team Yell Grunt has a level 29 Stunky and a level 30 Linoone. You get 2400 Pokédollars for winning.
Afterward, you battle another Team Yell Grunt. This one has a level 30 Liepard. You get 2400 Pokédollars for winning.
After that, there will be a cutscene, and you will get Opal's League Card.
To the west, you will battle Beauty Anita, who has a level 29 Clefairy and a level 30 Clefable. You get 2880 Pokédollars for winning.
The pokémon that you may see in this area are Axew, Dugtrio, Helioptile, Maractus, Trapinch, and Galarian Yamask. The pokémon that can be found in rustling patches of grass are Durant, Duskull, Hawlucha, Heatmor, Hippopotas, Silicobra, Skorupi, and Torkoal.
From the first patch of grass after the bridge from Hammerlocke, go west to find a ladder. You can optionally go up the ladder to find some water, where the pokémon that you can encounter by fishing are Dreadnaw, Goldeen, and Magikarp.
The area at the top of the ladder is a dead end, so go back down. If you go southeast from the ladder, you find a ledge where you can jump down. If you jump down from the ledge ledge, you will find 3 Ultra Balls.
To the west, you can optionally battle Medical Team Iwan and Evelyn, who have a level 31 Togetic and a level 31 Pawniard. You get 7440 Pokédollars for winning.
Go up either of the two ladders, and you can battle Backpacker Diane, who has a level 31 Sawk. You get 2232 Pokédollars for winning.
Go up the ladder northwest of the backpacker. To the left of the ladder, check on the sparkle to get 2 Fossilized Dinos (Sword) or 2 Fossilized Fish (Shield).
Go northeast from there to find TM15 Dig.
West of that, you can visit Cam's Pokémon Camp. Talking to Cam will add this as a Flying Taxi destination.
Go west from there and you can talk to the researcher, Cara Liss, If you have two different types of fossilized pokémon, she can revive them. Fossilized pokémon can be obtained in Bridge Field in the Wild Area if you talk to the Digging Duo near the Pokémon Nursery. Pay one of them 500 W and they will try to dig for fossils. The fossils that can be found are Fossilized Bird, Fossilized Dino, Fossilized Drake, and Fossilized Fish. The researcher can revive Arctovish (Fossilized Fish and Fossilized Dino), Arctozolt (Fossilized Bird and Fossilized Dino), Dracovish (Fossilized Fish and Fossilized Drake), and Dracozolt (Fossilized Bird and Fossilized Drake).
Go south from the tent, then west from the top of the ladder, and you will reach another ladder. Go down and follow the path to find a Light Clay.
Go east to jump down from the ledge, then go east past the backpacker, and go northeast to a ladder. Go up and you can optionally battle Model Nicola, who has a level 30 Skorupi and a level 30 Pawniard. You get 3600 Pokédollars for winning.
West of the model, check on the sparkle to get 2 Rare Bones.
Go northeast from the model, then go down the ladder. You can go east and optionally battle Backpacker Ruth, who has a level 31 Throh. You get 2232 Pokédollars for winning.
If you keep shaking the nearby berry tree, you can have a wild pokémon encounter with Greedent.
Go south from the tree, and you find a ledge that you can jump down, as well as some grass. Go south from this area to reach a narrow path that goes west. Go west along the path to find TM30 Steel Wing.
Go east from there, then west along the middle path to reach the ladder. Climb down and go southwest to find a sparkle. Check on it to get a Rare Candy.
Go back up the ladder and go east until you can go north. Go west from the berry tree and climb up the ladder. Go north from there and you will battle Artist Duncan, who has a level 29 Koffing and a level 31 Sudowoodo. You get 1984 Pokédollars for winning.
Go north and follow the path. It leads to Stow-on-Side.