Maybe Tracey. He was also an acquaintance of Ash. Since Tracey has his own unique skills and knowledge about Pokemon, his presence could bring new elements to the story. He could help Ash and other friends with things like Pokemon research or understanding some rare Pokemon behaviors.
In most Pokemon fanfictions, this is not the case. Ash is typically portrayed as a character who values his friends deeply. Fanfictions usually build on the strong bonds he has with his friends in the original series. However, there might be some very rare and out - of - the - ordinary fanfictions that take a different approach, but it goes against the general essence of the Pokemon story.
Ash would probably be devastated. He would feel like his world has been turned upside down. At first, he might not believe it and think it's all a big mistake. As the reality sinks in, he could start to isolate himself from others, even from his Pokemon for a while. However, his strong will would eventually kick in. He would use this as motivation to become stronger, not just in his Pokemon battles but also in his ability to face challenges alone, without relying on his so - called friends.
His friends would be extremely shocked at first. Misty might scream and be really confused about what's happening to Ash. Brock, on the other hand, would probably try to stay calm and start thinking of ways to reverse the transformation right away. They would all be worried about how Ash is feeling in his new form and if he's in any pain. They would also be concerned about how they can still communicate with him effectively, since he's becoming a Pokemon.
Well, it could be that Ash and his old friends meet up at a Pokemon tournament. There, they share stories of how their Pokemon have grown and evolved since they last saw each other. They might also team up to compete against a group of tough trainers, showing off their combined skills and the strong bond they have.
Ash is obviously a must - include. He's the main character in the Pokemon anime series, and his journey and growth are central to many fanfictions. Pikachu, his loyal Pokemon partner, is also extremely popular to include.
One idea could be Ash and his friends stumble upon a rare and powerful new Pokemon that has the ability to control time. They then have to figure out how to deal with this Pokemon without causing chaos in the timeline.
One possible reason could be a misunderstanding. For example, if his friends accidentally made a decision that cost Ash a big Pokemon battle or an important opportunity. Another reason might be if there was some sort of betrayal. Maybe one of his friends was secretly working with a rival and Ash found out. But again, these are very uncharacteristic scenarios for the Pokemon world.
Pikachu is a very likely candidate. It's Ash's most iconic Pokemon and has a deep bond with him. Whenever Ash is in trouble, Pikachu often steps up to protect him.
There could be a fanfiction where Ash and Pikachu enter a Pokemon tournament together. They face many tough opponents but their bond helps them win. For example, in one battle against a really strong water - type Pokemon, Pikachu is in trouble but Ash's trust in Pikachu gives Pikachu the extra boost to use a super - charged thunderbolt and win the match.