Years ago, in the Lapidarian Highlands, when Diantha was filming a movie, a thick fog arose and Diantha got lost. Diantha had entrusted Kathi Lee with her Gardevoir, and when Kathi Lee and Diantha's other staff went to search for her, Gardevoir came out of its Poké Ball. Due to Diantha's and Gardevoir's strong bond, their hearts were calling out to each other, and Kathi Lee and the other staff were able to find Diantha with Gardevoir's guidance.
In the present day, when Diantha was preparing for an exhibition match against Magnus, Kathi Lee tried to hold back the press and fans in front of Diantha's dressing room, saying she would not accept any interviews or meetings that day. She later rudely interrupted Diantha's conversation with Professor Sycamore, who wanted to make an appointment with Diantha to study her Key Stone. Kathi Lee let him know Diantha wouldn't have any time to visit him. Sycamore then tried to change her mind by flirting with her, but instead ended up getting hit with a book.
Kathi Lee appeared again in Championing a Research Battle!. She was riding in a helicopter that dropped Diantha off at the grass field where Ash and his friends were resting at. At the end of the episode, she arrived to pick Diantha up.