After you explore the small town of Ballonlea, you enter the Ballonlea Stadium for the Gym Challenge.
Explore the Stadium
When you first enter Ballonlea Stadium, there will be a cutscene. You will get Marnie's League Card.
Afterward, talk to the Ball Guy to get a Love Ball. It works best on pokémon of the same national pokédex number as, but the opposite gender of, your currently active pokémon.
You can talk to the Poké Kid and trade a Galarian Yamask to receive Eve's non-Galarian Yamask, nicknamed Masky.
When you are ready, talk to the person at the north end of the stadium lobby to begin the Gym Mission.
Ballonlea Stadium Gym Mission
In this gym, you will be asked quiz questions. If you get the right answer, your pokémon's stats will temporarily increase. If you get the wrong answer, the stats will decrease. After the cutscene, go east to arrive in the Gym Mission area.
First, you will battle Gym Trainer Annette, who has a level 34 Spritzee and a level 34 Slurpuff. During the battle, you will be asked if you know about Fairy type's weaknesses. Answer: Attack and Sp. Atk go up one stage upon answering correctly. You get 3264 Pokédollars for winning.
Next, you will battle Gym Trainer Teresa, who has a level 34 Swirlix and a level 34 Aromatisse. During the battle, you will be asked what the previous trainer's name was. Answer: Speed goes up one stage upon answering correctly. You get 3264 Pokédollars for winning.
Next, you will battle Gym Trainer Theodora, who has a level 35 Morgrem and a level 35 Gardevoir. During the battle, you will be asked what this trainer eats for breakfast every morning. Answer: Defense and Sp. Def go up one stage upon answering correctly. You get 3360 Pokédollars for winning.
After that, you have a chance to heal up your pokémon. Then when you are ready, talk to the person, or go into the door to the right of the person and go up the ramp, to reach the battlefield.
Gym Leader Opal
Gym Leader Opal has a level 36 Galarian Weezing, a level 36 Mawile, a level 37 Togekiss, and a level 38 Alcremie. During the battle, you will be asked:
- What is Opal's nickname? Answer: Speed goes up two stages upon answering correctly.
- What is Opal's favorite color? Answer: Defense and Sp. Def go up two stages upon answering correctly.
- How old is Opal? Answer: *. Attack and Sp. Atk go up two stages upon answering correctly.
You get 6080 Pokédollars for winning.
You get the Fairy Badge. You will now be able to catch pokémon up to level 45. You also get TM87 Draining Kiss, and you get the Fairy Uniform.
At Poké Marts, you can now purchase Ultra Balls and Super Repels.
After the Battle
When you leave the Stadium, there will be a cutscene. You can go directly to Hammerlocke with Opal, or you can say that you will find your own way if you wish to stay in Ballonlea longer.
After you arrive in Hammerlocke, approach the Stadium. There will be a cutscene.
Afterward, keep going east and you will find Sonia near the Hammerlocke Station. Approach her and there will be a cutscene.
After that, go east and approach Hop. There will be a cutscene.
Go east to reach Route 7.