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.
He could make friends with Dawn. She's a well - known character in Sinnoh and her knowledge of Pokémon contests could be really helpful to Ash. Another potential friend could be Barry. His energetic and competitive nature would make for some interesting interactions with Ash.
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.
One possible plot could be Ash feeling lonely and deciding to go on a solo journey to prove himself. He faces various challenges alone and in the process discovers his own inner strength. He might encounter some Pokémon that become his temporary companions during battles but then part ways, emphasizing his solitude.
One possible reason could be jealousy. Maybe Ash has achieved more in his Pokemon journey than his friends, and they can't handle it. Another reason might be some misunderstanding. For example, an enemy could trick Ash's friends into thinking Ash has done something bad. Or perhaps there's some sort of power struggle. If there's a powerful item or a rare Pokemon involved, and Ash is the main contender, his friends might be tempted to betray him for their own gain.
One popular 'ash friends alola fanfic' could be 'Ash's Alola Adventures'. It often focuses on Ash's new experiences and friendships in the Alola region. Another might be 'Alola Friends: Bond Beyond Battle' which delves into the deeper relationships between Ash and his friends during his time in Alola.
The fanfiction might also explore Ash's inner turmoil. He could struggle with self - doubt, thinking that he was not a good enough friend. However, as he faces various challenges on his own, he realizes his own worth and that the abandonment was more about his friends' own issues rather than his shortcomings.
It could be a trainer who takes advantage of Ash's loneliness. This trainer might trick Ash into giving up his Pokémon or getting into dangerous situations. For example, he could tell Ash that there's a special place where he can find friends if he follows him, but it's actually a trap.