After you make your way through the darkness of the Glimwood Tangle, you reach the town of Ballonlea.

Explore Ballonlea

Go west from the Pokémon Center and go up the stairs. To the west, at the end of the path, there is an artist who wants you to wear a Fire-themed outfit. You can go to Hammerlocke and talk to the cashier at the boutique to purchase the Fire Type Tracksuit Jacket for 10180 Pokédollars and the Fire Type Trackie Bottoms for 8620 Pokédollars. Make sure that you are wearing them, then you can go back to Ballonlea talk to the artist to receive TM78 Acrobatics.

Go into the house that the artist is standing next to, and talk to Frank to give him the Old Letter. You will get a Choice Scarf.

Check in the space between this house and the one next to it to find 2 Big Mushrooms.

Go into the house to the right of that, and talk to the person in the kitchen to get TM77 Hex if you are playing Pokémon Sword, or TM42 Revenge if you are playing Pokémon Shield.

You can say Yes to the Pokémon Breeder in this house to battle Pokémon Breeder Elena, who has a level 30 Dottler. You get 2880 Pokédollars for winning. Afterward, you get an Eviolite. It increases the Defense and Sp. Def. of a pokémon that hasn't evolved to its final form yet.

Go outside, then go east, and go southeast from the bridge to the Stadium to find TM21 Rest.

Go southwest from there and check on the sparkle to find a Balm Mushroom.

When you are ready, go north to enter the Ballonlea Stadium.