Honestly, I haven't come across any popular 'Harry Potter Vomiting Fanfiction' specifically. Fanfiction usually focuses on more common themes like relationships (like Harry and Hermione's relationship in some fanfics), adventures, or exploring different magical aspects. Vomiting might be a really out - there and not so mainstream idea for a fanfic, so it's hard to point to any particular ones.
One possible reason could be that he was poisoned. In the wizarding world, there are many dark spells and potions that could cause such a reaction. Another reason might be extreme motion sickness if he was on a wild magical ride, like on a particularly unruly broomstick or a flying magical creature.
Well, 'tails vomiting fanfiction' could potentially be a piece of fan - made writing that focuses on a character named Tails in a rather unappealing situation of vomiting. Maybe it's part of a more complex plot in a fan - created universe where Tails gets sick and this vomiting incident has consequences for the story, like other characters having to take care of him or it being a sign of some sort of danger or illness in that fictional world.
No, it doesn't seem like it would be a common type of fanfiction. Fanfiction usually focuses on more positive or exciting aspects of characters, like their adventures, relationships, or heroic deeds. Vomiting is not a typical focus, so 'tails vomiting fanfiction' is likely a very niche and unusual creation.
I'm not sure there are a lot of specifically 'vomiting' centered fanfictions about James Potter that are widely known. You could try searching on major fanfiction platforms like Fanfiction.net or Archive of Our Own. Use filters to ensure the content is appropriate for all ages and look for stories that might mention James Potter in various situations that could potentially include something related to the concept, but it might be a rather rare find.
Well, one possible plot could be a character getting food poisoning and the story revolving around their friends or family taking care of them during this difficult time.
Obviously, Ash is a central character since it's about him vomiting. Pikachu is likely to be there too, probably looking worried about Ash. Maybe Misty would be in the story as well, scolding Ash for getting into a situation that made him vomit or trying to take care of him.
There may be very few, if any, pieces of fanfiction directly centered around vomiting and diarrhea. Fanfiction usually focuses on more appealing aspects of characters and their relationships. You might be better off looking for stories where a character gets sick in a more general sense and then expands your search from there.
It's not a common type. In the vast world of Harry Potter fanfiction, you'll find a lot more stories about Hogwarts during different eras, the relationships between the main trio, or the exploration of the wizarding world's politics. 'Breeder fanfiction' is more of a specialized sub - genre that only a small subset of fans might be interested in, as it delves into family - building and genetic - like concepts which are not as central to the general appeal of the Harry Potter series.