The fanfic could start with Ash feeling a strange energy while in a battle. Then, boom, he's a Charizard. His appearance would change completely. He would have wings, sharp claws, and a long tail. His opponents in battles would be terrified of this new form. But Ash, being Ash, would still have his kind heart. He might use his new form to protect other Pokémon from danger, like fighting off a group of poachers. And his journey as a Charizard would be filled with adventures, like exploring new regions that are difficult for humans but easy for a flying Pokémon like him.
Well, one possibility is that Ash, after some magical or scientific mishap, suddenly transforms into a Charizard. He might struggle at first to control his new powerful form. For example, he could accidentally set things on fire with his newfound fire - breathing ability. His friends would be both shocked and worried, trying to figure out how to turn him back. Maybe Pikachu would be especially confused, not knowing how to interact with his transformed trainer.
One plot twist could be that Ash - as - Charizard loses his memory of being human. His friends have to find a way to remind him who he is. Another could be that the transformation is not a random accident but part of an evil plan by a villain who wants to use Ash's new form for their own purposes.
One possible plot could be that Ash realizes Charizard has grown too powerful for the current region he's in and decides to release it so it can find a more challenging environment. Maybe it goes off to a far - off mountain range where it battles and befriends other powerful Pokémon.
The plot could be that Ash is in Kalos to participate in a special Pokémon tournament. Misty hears about it and decides to come support him. Charizard, of course, is Ash's main battling Pokémon. Along the way, they meet a new type of Pokémon that is causing trouble in the region. They have to figure out a way to stop it, with Charizard using its powerful attacks. And in the end, Ash wins the tournament with the help of Misty and Charizard.
It could be about Ash and his Charizard training to master the blue flames. Maybe they encounter a powerful enemy that can only be defeated with this new, more powerful form of Charizard's flames.
Maybe in the fanfic, Ash and his friends are exploring an ancient ruin. Charizard, being curious, wanders off and accidentally triggers a booby - trap. It gets severely injured. Ash is then on a race against time. He needs to find a way to heal Charizard before it's too late. Along the way, he meets a mysterious old trainer who gives him some advice on a rare and powerful healing method. But the method requires Ash to face his own inner demons and prove his worth as a trainer.
One possible plotline could be that Ash and his Mega Charizard embark on a journey to a new, uncharted region. There, they face a powerful new villain with a team of never - before - seen Pokémon. Along the way, Ash has to train Charizard even further to unlock new Mega Evolutions. They meet new friends who help them in their battles and exploration.
One possible plot could be that Ash hears of a powerful Pokémon tournament where the winner gets a special wish. He decides to enter with his current team, battles through tough opponents, and in the final, he faces a trainer with a Charizard. After winning, he uses his wish to get his old Charizard back.
A common theme is friendship. Ash and Charizard have a deep bond, and many fanfics explore how their friendship endures through tough times.
Well, it could be about Ash somehow magically being transformed into a Latias. Maybe he then has to deal with the powers and instincts that come with being a Latias. He might try to find a way to turn back while also exploring the world from a new perspective as a Pokemon.
Well, perhaps in the fanfic, Ash turns into a girl because of a curse. As a girl, Ash could start to see the Pokemon world from a different perspective. Maybe she would form new relationships with her friends, like Pikachu being more protective. And she might have to enter Pokemon contests instead of battles at first due to the new appearance, but then find a way to get back into battles and show that she's still the same strong trainer inside.