After checking out the Battle Royals at the Battle Royal Dome in Royal Avenue, go northeast to explore Route 7.
Go north to the Captain's barricade, then go east down a ramp to the beach. Go to the south end of the beach and use Stoutland to find a hidden Net Ball.
Use Lapras to Surf in the water.
In the southern part of the water, you can battle Swimmer Dakota. He has a level 18 Basculin and a Psyduck. You get 432 Pokédollars for winning.
If you go to the far north end of the water, go west and land on the beach. Then go south to find a hidden Pearl on the rock.
If you go north along the sand, you can find rustling sand. Approach the sand to battle pokémon.
Go farther north and go up the ramp to find a Max Repel at the end.
Go back down the ramp, then get into the water. In the northwest part of the water, you can battle Swimmer Tiare. She has a level 19 Alomomola. You get 456 Pokédollars for winning.
To the east, you will see an Antidote underwater. Just swim over it and press A to get it.
Nearby, you can battle Swimmer Casey. He has a level 18 Surskit. You get 432 Pokédollars for winning.
You can go south from there to find a separate beach area. Go south and you find a small pool that you can fish in. To the left of that pool, you find TM32 Double Team.
Southwest of the small pool, you can battle Swimmer Vanessa. She has a level 18 Shellder. You get 432 Pokédollars for winning.
You can go west from Vanessa to jump down a one-way ledge, and from there you can Surf west to the main road.
That is all that you can find in Route 7, so when you are ready, go west to Wela Volcano Park.