After you win the Basic Badge from Cheren in Aspertia City, Bianca tells you to seek the next badge in Virbank City, just past Floccesy Town.
Get the Habitat List
From Aspertia City, go to Route 20, which is just past Floccesy Town. Right when you're about to exit Floccesy Town, Bianca rushes up to you. She upgrades your pokédex to add the Habitat List. This is a very handy feature that lets you see which pokémon are in which areas.
To use it, open your pokédex. Tap Habitat List in the bottom left. On the right, you will see a list of places that you have been to. If you tap one of those places, you will see a list of pokémon that can be found in that area! Very helpful! Just remember that it will only list pokémon that are already in your pokédex, so be sure to battle a lot of people so their pokémon will be added to your pokédex.
Go to Virbank City
Now that you have the Habitat List, you can continue walking to Virbank City. First, go to the eastern part of Route 20, where a hiker is blocking the stairs. He notices your gym badge and challenges you to a battle. Hiker Jerome has a level 11 Riolu.
After you defeat Hiker Jerome, go down the stairs to find Preschooler Albert. He has a level 10 Psyduck.
When you go south from Preschooler Albert, Hugh and Cheren arrive. Cheren shows you some dark tall grass to the south. He says that in the dark grass, sometimes two pokémon will attack at once. Then Cheren gives each of you some Pecha Berries before going back to Aspertia City.
Hugh will be determined to become stronger than Cheren. He'll go into the dark grass. South of Hugh, there is a Great Ball.
To the east of the dark grass, you find Preschooler Lin. She has a level 10 Lillipup.
North of her and to the east in the grass, there is an Antidote.
Up north you meet Nursery Aide Kimya. She has a level 11 Dunsparce.
Go north from Kimya to find a Dire Hit.
East of there, you find the twins Lia and Lily. THey send out two leve 9 Sunkerns that you have to battle simultaneously. You will send out the first and second pokémon in your party.
East of the twins, you find the gate to Virbank City. On the way through, the gatekeeper lady will give you some Great Balls.