BioRebecca was first seen watching the battle on the road between Anthony's Hitmonchan and Pikachu. After the battle she introduced herself to Ash and his friends and told them that her father Anthony's holed himself up in the mountains and wouldn't come home at all despite the pleading from her. Ash and Brock agreed to enter the tournament in order to beat Anthony so that he'd come to his senses and return home to his family.
In the P-1 Grand Prix tournament, Rebecca sat in the stands with Misty as they watched all the fights hoping that her father would loose. After loosing, Anthony asked his daughter Rebecca to forgive him for worrying so much and they quickly made up. Thankful for Ash's help, she waved goodbye to Ash and his friends after Ash released his Primeape to her father.