Yarrow serves as the Grass-type Gym Leader of Turffield Stadium in the Galar region. His background is deeply rooted in agriculture, having grown up as the son of farmers. He honed his strength through farm work alongside his Grass-type Pokémon from a young age, an experience that directly shapes his training and battling philosophy, emphasizing endurance and close cooperation.

Physically imposing yet gentle in demeanor, Yarrow struggles to exert full effort against opponents he perceives as weaker. He prioritizes enjoyment and mutual satisfaction in battles over victory or defeat, a trait contributing to his placement as the first Gym Leader challengers face. His daily routine involves managing Wooloo herds at his Turffield farm, utilizing Yamper for herding. These Wooloo often wander, leading to recurring scenarios where he chases them through town, sometimes prompting assistance from the community.

Within official animation, Yarrow appears across multiple episodes. He locates a runaway Wooloo belonging to Hop, identifies its ownership tag, and arranges its return via Flying Taxi. His participation in the Champions Cup is documented through a televised battle where he deploys his Dynamax-capable Eldegoss against Nessa's Drednaw. Later, he provides commentary on Champion Leon during an interview segment. He also participates in the Galarian Star Tournament opening ceremony, following scenes showing him engaged in farm work with his Wooloo.

Regarding relationships, Nessa identifies him as her rival, though he does not reciprocate this view, stating his only rival is himself. Design elements reflect his specialty and background: his Gym uniform bears the number "831," referencing Wooloo's Pokédex number and the Japanese word "yasai" (vegetables) through goroawase wordplay. The Turffield Orchards logo appears on his attire. Demonstrating notable physical strength, he effortlessly maneuvers hay bales weighing over 770 pounds during Gym missions.