Pokemon and Yu - Gi - Oh Zexal: Ash and Kari Fanfiction - Who are the best characters to include in a crossover story?

In this kind of fanfiction, Ash and Kari are the central characters. But from Pokemon, Serena could be included. She has her own dreams and skills related to Pokemon performances. In Yu - Gi - Oh Zexal, Tori would be a good addition. She's a friend of Yuma and can bring in the perspective of someone who is learning about dueling. Also, Gary from Pokemon could be added. His rivalry with Ash can add some tension and competition. And from Yu - Gi - Oh Zexal, Bronk can be included. He's a regular guy trying to improve his dueling skills, which can create some relatable moments in the story.