In this fanfiction, I think his Pokémon, especially Pikachu, would definitely be by his side in the hospital. Also, his other friends from his journey like May or Dawn might come to see him and bring him some get - well - soon gifts.
His friends like Misty and Brock would probably visit him.
Well, it's very likely that Professor Oak would visit Ash in the hospital. He has always been like a mentor to Ash. And maybe some of the Gym Leaders that Ash has befriended over the years would also drop by. They might share their own experiences of getting injured and recovering to give Ash some hope and motivation to get better.
Professor Oak could also come to visit Ash. He might bring some rare Pokémon medicines from his lab. And of course, Ash's mom would be there. She would cook all of Ash's favorite foods and make sure he takes his medicine on time and gets enough rest.
He might meet an old Pokémon expert who gives him tips on hatching the egg.
Maybe it's a legendary Pokemon in disguise. In some fanfictions, legendary Pokemon often play important roles. It could give Ash the egg as a test or because it senses that Ash has a pure heart. Another possibility is that it could be a young trainer who can't take care of the egg anymore and trusts Ash to do a good job.
One possible fanfiction could be that Ash gets injured during a Pokemon battle and is rushed to the hospital. Serena, being worried sick, stays by his side the whole time. She might bring him his favorite Pokemon treats to cheer him up while he recovers.
He might meet new Pokémon trainers in Alola. Maybe some young kids who are just starting their own Pokémon journey.
He might meet Pikachu first. Since Pikachu is his closest and most loyal Pokemon friend, it would be likely that Pikachu would be by his side when he wakes up. Pikachu could be really confused at first but still show concern for Ash in his new state.
There's also a chance that an old enemy from Ash's past resurfaces. This enemy, who has a long - standing grudge against Ash, could find a way to use Ash's Pokemon to get revenge. They might have developed new techniques or powers over time that allow them to influence the Pokemon's loyalty.
In the 'pokemon ash in the hospital fanfiction', it could be that Ash got poisoned during an encounter with a new and dangerous Pokémon. While in the hospital, he starts to have strange dreams about a powerful Pokémon he has never seen before. His friends come to visit him, like Misty and Brock. Misty might scold him a bit for being too reckless but also show her concern. Brock could be using his knowledge of herbs to see if there are any that can help Ash's recovery. And all the while, Ash is thinking about getting back on his journey as soon as possible.
There might be a young and inexperienced trainer who is lost. Ash, being the more experienced one, decides to help the trainer find their way. This new character could look up to Ash and in the process, Ash learns more about himself as a role model. It would be an interesting dynamic as Ash is usually the one being guided by his friends.
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.