One idea could be that Dawn and Barry team up for a special Pokemon tournament. They train together, sharing their unique training methods. Dawn might teach Barry about the importance of bond with Pokemon, while Barry shows Dawn some new battle strategies.
A third plot could be set in a post - apocalyptic Pokemon world. Dawn and Barry are among the few trainers left. They must find a way to restore the balance in the Pokemon world. They start by gathering different types of Pokemon and trying to revive the ecosystems that have been damaged.