It could be about Ash achieving the ultimate goal of becoming the Kanto champion. Maybe it details his journey, the battles he had to overcome, and the growth he experiences along the way to claim the title.
I think Brock and Misty could be main characters too. They travel with Ash in Kanto. Brock with his knowledge of Pokémon care and Misty with her own skills as a trainer could play important roles in Ash's journey to become the champion in this fanfiction. Maybe they offer advice, support, or even join in some of the battles.
Ash can be developed further by showing his insecurities as a champion. Maybe he starts to doubt if he really is worthy of the title, and this makes him train even harder. He could also develop new relationships with other trainers in Kanto, learning from them and teaching them in return. Another way is to show his growth in handling the political side of being a champion, like dealing with the Pokémon League's bureaucracy.
One plot idea could be Ash facing a new and powerful villain who has a vendetta against all the previous Kanto champions. This villain could be trying to rewrite the history of the Kanto region's Pokémon battles. Another idea is Ash having to defend his champion title against trainers from other regions who believe he doesn't deserve it because he's from a relatively small town. A third plot could involve Ash finding a rare and mysterious Pokémon in Kanto that has the power to either greatly enhance his team or put them in great danger, and he has to figure out how to handle it while still being the champion.
The unknown champion could be a reclusive hermit - like character who has been living in seclusion in a forest. They have trained their Pokémon in harmony with nature and have a very different approach compared to the more mainstream trainers. Maybe they are an old - timer who has seen different eras of Pokémon training.
Ash's character in the Kanto fanfiction with Lillie might develop in terms of his leadership skills. He often takes the lead in their adventures, making decisions that affect both of them and the Pokemon they encounter. Lillie's development is more about self - discovery. In Kanto, she discovers her own strengths and weaknesses. She realizes that she has a natural ability to calm down agitated Pokemon, which she uses to help Ash during battles. Their time in Kanto is filled with challenges that shape their characters in different but complementary ways.
Their relationship develops as they face challenges together. In Kanto, every new Pokemon they encounter, every Gym battle Ash participates in, Serena is there. She cheers him on, and through this shared experience, they grow closer. For example, when Ash loses a battle, Serena is there to comfort him, and this makes their bond stronger.
In the Kanto setting, they could explore new places together. Like when they visit the Safari Zone, they might share exciting moments while trying to catch different Pokemon. These shared experiences can lead to a deeper understanding and more affection between them. Also, meeting new trainers and learning from them could be another way. Maybe they meet an old couple who have been traveling together for years with their Pokemon, and this inspires Ash and Serena to be closer.
Well, in an 'ash unknown champion' fanfiction, the plot might involve Ash getting lost in a mysterious region. There, he stumbles upon an unknown champion who is facing some sort of problem, like a group of poachers targeting their rare Pokémon. Ash decides to help the champion, and in the process, they exchange their Pokémon training techniques. As they work together, Ash realizes that there are so many new ways to approach Pokémon battles that he hadn't known before.
A common theme is friendship. Ash and May's relationship as friends growing and evolving during their time in Kanto. Another theme is growth. Both of them grow as trainers, Ash in his battles and May in her coordinating skills.