In this genre, characters can also develop through facing challenges together. Suppose they enter a big tournament that combines beauty and battling. They have to deal with difficult opponents and strict judges. Ash might develop his patience as he waits for the beauty part of the competition to finish before his turn to battle. The battling beauty characters could develop their courage as they face stronger opponents in the battling rounds. They could also learn from each other's mistakes during the tournament and become better trainers overall.
The characters can be developed through their relationships. If there is a female lead in the fanfiction who is a battling beauty, her relationship with Ash could grow. She could teach Ash about the fashion and presentation side of the Pokemon world, while Ash teaches her about the raw power and strategy of battling. This mutual learning can change their personalities. Ash could become more refined in his approach, and the female lead could become more confident in her battling abilities.