In some fanfictions, the other characters' reactions are quite complex. For example, Team Rocket might see Ash fainting as an opportunity to steal his Pokemon at first. But then, they might realize that without Ash, there's no real fun in their evil schemes. So, they end up helping in their own clumsy way. Ash's other Pokemon friends would gather around him, with some using their special abilities to try and heal or revive him, while others would just be there for moral support.
When Ash faints in fanfiction, his friends' reactions can vary. For instance, Serena might cry and hold his hand, praying for him to wake up soon. Clemont would use his scientific knowledge to see if there's any way to help. Bonnie would be panicking and asking everyone to do something quickly. And his rivals, like Gary, might initially make a sarcastic comment but deep down be a bit worried too.
His friends like Pikachu would be very worried. Pikachu would probably stay by Ash's side, trying to use its electric shocks gently to revive him. Misty might scold Ash for being so reckless but also show concern by getting water to cool him down. Brock would immediately start checking Ash's vital signs and try to figure out what went wrong.
In certain fanfiction stories, Ash could faint as a result of a psychological shock. Imagine if he discovers that one of his beloved Pokemon has been mind - controlled by an evil organization. The sheer horror and disbelief could be so overwhelming that he faints. Additionally, he might be caught in a powerful psychic attack from a very strong psychic - type Pokemon that not only weakens his physical state but also his mental state, leading to his fainting.
Some characters might immediately rush to their side. They could be the managers or fellow members, showing concern and trying to revive them. They may call for medical help right away.
Pikachu would probably be very protective. It might zap anyone who tries to make fun of Ash. Misty would likely be shocked at first, but then she'd start taking care of him like an older sister, making sure he's clean and fed. Brock, being the nurturing type, would probably be the one to find practical solutions for taking care of baby - Ash, like finding proper diapers in the Pokemon world.
Hermione would likely be the first to rush to his side. She would immediately start using her knowledge of magic to try and figure out what was wrong with him. She might cast diagnostic spells and try to find a cure if it was something she could handle on her own.
His Pokémon might try to cheer him up. Pikachu, for instance, could use its cute antics to make Ash smile. It might nuzzle against him or do some of its signature electric tricks in a playful way. They have a very close bond, so the Pokémon would sense his sadness and do their best to make him feel better.
Pikachu might be a bit confused at first. He's used to Ash's adventures mainly being about Pokémon battles and training. But he would soon get used to it and might even play a role in making the 'date' more fun. For example, using his electric attacks to create some light shows for them.
Brock would be more understanding. He's always been interested in girls, but he also values friendship. So he would probably offer his support to Ash, while also maybe giving some advice on how to act more 'ladylike' if that's what the situation calls for. As for the other Pokemon in Ash's team, they might not fully understand the concept of crossdressing, but they would sense that Ash is still their trainer and would protect him (or her in this case) as usual.
Typically, teachers first call for help. They might ask another student to go to the school nurse or the nearest office. Then, they try to make the fainting student comfortable. For example, they may loosen any tight clothing like ties or scarves.
There are also fans who might be a bit angry or disappointed. They see Ash as a symbol of hope and perseverance in the Pokémon world, and having him die in a fanfiction goes against what they expect from the character. However, they also understand that it's part of the creative freedom in fanfiction writing.
Ash would probably be very shocked and hurt. Pokemon are like his family, and for Misty to steal one would go against everything he stands for.