Charizard might initially be confused and a bit frustrated. It's used to Ash as he was before. But then it would come to accept Ash's new form. Charizard would be very protective in battles, using its powerful attacks to keep Ash safe. It might also try to learn from Ash's new fairy powers, like how to be more in tune with nature like fairies are.
Some of his Pokémon like Pikachu might be very protective. Pikachu would stay close to Ash at all times, being extra vigilant in case any danger comes while Ash is in this new form. It would also be curious and might try to play with Ash's new fairy features, like his wings if he has any.
The unique character development. When a Pok mon is pregnant in a fanfic, it gives an opportunity to explore the Pok mon's personality in a new light. For example, how it copes with the physical and emotional changes. It can also show the relationship between the Pok mon and its trainer in a different way, like increased protectiveness from the trainer.
You can start by looking on fanfiction websites like FanFiction.net or Archive of Our Own. These platforms have a wide variety of Pok mon fanfics, and you can use the search function to specifically look for ones related to the 'pregnant' theme. Just be sure to read the ratings and reviews to ensure the quality.
The plot might involve Ash being cursed to turn into a fairy. He then has to go on a journey to find a way to reverse it. Along the way, he meets other fairy - type Pokémon and fairies who either help or hinder him. He could learn about the fairy world's culture and traditions, and this knowledge could be the key to breaking the curse. Maybe he has to prove himself worthy in some way, like by helping the fairies solve a big problem in their realm.
The Pokemon that have been with Ash for a long time, like Snorlax, might have a deeper connection with him and be able to sense that it's still Ash, even though he looks like a hedgehog. Snorlax might be more accepting right away and try to protect Ash from any potential danger. On the other hand, the newer members of his team might be more likely to question whether this hedgehog - like Ash is still their rightful trainer. But as time passes, they would all start to realize that Ash's spirit and his bond with them haven't changed, despite his physical transformation.
Ash could get angry. He has a strong sense of justice, and he might feel that May has violated their friendship. He could challenge her, not in a violent way, but more in a way to get an explanation and to try to make her see the error of her ways. He would likely be determined to show her that what she did was wrong.
Ash would likely be shocked at first. He's so used to seeing the good in people, especially fellow trainers. But then he'd probably get angry and determined to set things right. He has a strong sense of justice, so he wouldn't let the betrayal go unpunished.
Ash would be extremely devastated. Pikachu is not just his Pokémon but also his closest friend. He would likely first try to reason with Pikachu, not believing that Pikachu could truly betray him. He might be in denial for a while.
It could be a fan - made story where the character Ash is somehow transformed into a Latios. It might explore new adventures, powers, or relationships that come with this transformation.
Ash would probably be initially shocked. He is used to seeing the good in people and would not expect such a betrayal from Cynthia. He might stand there in disbelief for a moment, unable to process what has just happened.
Ash might be heartbroken at first. He'd feel a deep sense of loneliness and confusion.