In the fanfic, Ash could enter a major coordinator competition where he faces off against some of the toughest opponents. He might struggle at first because he's used to traditional Pokemon battles. But as the competition progresses, he starts to understand the nuances of coordinator battles better. His friends could also play important roles, like Misty giving him advice on how to make his Pokemon's water - based attacks look more appealing, and Brock helping with Pokemon health and grooming to ensure they look their best during the shows.
Perhaps the story could involve Ash being transformed into a Pokémon through some magical or scientific experiment gone wrong. As a Pokémon, he would join a group of other Pokémon on a journey. He might face challenges like being hunted by Pokémon hunters or having to prove himself to a Pokémon tribe. Along the way, he'd also learn about the different perspectives of Pokémon in their own world.
Ash would likely have to change his training methods. He'd focus more on presentation. For instance, instead of just making Pikachu use Thunderbolt for power, he'd teach it to use it in a more artistic way, like creating a lightning display. His Pokemon would need to learn new skills for the performance aspect.
Obviously, Ash is one of the main characters. He is the one on the journey to become a Pokemon master. Pikachu would also be a key character as Ash's loyal partner. There might also be Brock and Misty, his old friends, who could make appearances and help him out on his journey.
It could be Team Rocket. Since they always cause trouble for Ash in the original series, in this fanfic, they might see Ash's transformation into a Pokémon as an opportunity to capture him and use him for their evil plans.
In many fanfictions, Ash achieving the status of a Pokemon Master often involves him having extraordinary battles. He might defeat powerful legendary Pokemon that no one has ever tamed before. His Pikachu could evolve into a more powerful form, which gives him an edge in battles. Also, his bond with all his Pokemon, not just Pikachu, becomes so strong that they can execute complex strategies without any communication barriers.
Well, one interesting plot point could be Ash facing extremely tough opponents that he has never encountered before. This would test his skills and strategies to the limit. Another might be Ash making unexpected alliances with other trainers or even some Pokemon. It could also be that he discovers a new type of Pokemon evolution that changes the game in his journey to become a Pokemon master.
Well, in such a fanfiction, Ash might experience the life of a Pokemon in a very different way. He could understand their thoughts and feelings more deeply. Maybe he'd have to learn how to use Pokemon moves in his new form, which would be a really strange and exciting adventure for him.
It could be a powerful and evil Pokemon trainer who wants to capture Ash in his new Pokemon form. This trainer might be after Ash because he believes that a human - turned - Pokemon has some special power or value.
His Pokemon could be his potential allies. They've been with him through thick and thin and would likely still support him even with his new vampire state. As for enemies, there might be those in the Pokemon world who fear or dislike vampires and would see Ash as a threat. Maybe some powerful and evil Pokemon trainers who want to use his new situation against him.