One possible scenario could be that Pikachu is exposed to a strange type of energy. This energy mutates its genetic structure, slowly transforming it into a human form. At first, Pikachu might be confused and scared, not understanding its new body. But as time passes, it starts to learn about human ways, like walking on two legs and using its hands to pick things up.
Pikachu might find it difficult to communicate at first. Since it was used to making 'Pika - pika' sounds, it would have to learn human languages. It could start with simple words and phrases, and as it becomes more proficient, be able to have complex conversations. For example, it might try to explain to Ash how strange it feels to have fingers instead of paws.
Well, it could start with Ash being transformed into a Pikachu in a mysterious forest. His friends are initially confused but soon realize it's him. As a Pikachu, Ash discovers new abilities he didn't know about before. He might be able to sense things like incoming danger more acutely. He could also have a hard time convincing his other Pokémon that he is still their trainer. Throughout the fanfiction, there could be a series of comical and exciting events as he tries to adapt to his new form and find a way to reverse the transformation.
Some Pokémon might be more protective of her. For example, her long - time friends like Ash's other Pokémon could become very over - protective, seeing her as more vulnerable in her new female form. Other Pokémon that were once rivals might now view her differently, perhaps being less aggressive towards her.
Well, in this fanfiction, if Ash turns into Pikachu, it might lead to a story where Pikachu - Ash discovers new aspects of the Pokémon world. For example, he could experience the world from a Pokémon's perspective, understanding their fears and joys more deeply. He might also have to deal with other Pokémon who don't immediately recognize him as Ash and react in different ways to this strange Pikachu.
His friends would be very shocked at first. Misty might be a bit worried and try to find a way to turn him back quickly. Brock, on the other hand, would be more curious and start observing Ash - as - Pikachu to see how his behavior has changed. His Pokémon friends would also be confused. Pikachu himself might be both excited to have a 'Pikachu - like' friend but also a bit sad that his trainer is in this strange state.
One possible plot could be that Pikachu, as a girl, goes on an adventure to find a special type of berry that is said to have magical powers. Along the way, she meets other Pokémon who initially don't accept her because she's different. But through her kindness and determination, she wins them over and they all help her find the berry in the end.
It could start with the boy having a really strong wish to be a Pikachu. His intense desire somehow triggers a magical event that turns him into one. Once he's a Pikachu, he discovers that the Pokémon world is not as simple as he thought. He has to face challenges like avoiding being caught by Pokémon trainers and finding food suitable for a Pikachu in the wild.
One possible scenario could be that in this fanfiction, the change forces Kratos to view the world from a different perspective. As a girl, he might face different challenges and reactions from the other characters. Maybe the gods who once feared him now underestimate him, leading to some interesting power dynamics.
Perhaps in a parallel universe, Superman is born as a girl. This version of her grows up with different experiences and challenges. She could be more in tune with female issues in society and use her powers to fight for gender equality as well as the usual superhero stuff like saving the world from villains and disasters.