Piers is the Gym Leader of the Spikemuth Gym and those that defeat him receive the Dark Badge. He is also the boss of Team Yell. In the games, Pokémon Sword and Shield, he passes the title of Gym Leader to his little sister,
Marnie.
Ash Ketchum was to face off against
Marnie in the Pokémon World Championships but in an attempt at making her win a walkover victory, the Yell Gang feed
Ash Ketchum misinformation regarding the venue of the match and sends him to Spiketown, where he encountered Marie's older brother
Piers! Piers drove Ash to the real venue in Wyndon on his motorcycle, and on the way he told him how Marie feels about the Championships. He then stayed to watch the match.