He could die in a battle against a very powerful and evil Pokemon. Maybe a new, extremely strong legendary Pokemon that he underestimated, and it managed to land a fatal blow.
Another way could be through some sort of illness or poison that he gets exposed to while exploring a new and dangerous area in the Pokemon XYZ world. Since he's always out there exploring, he might come across a deadly plant or a poisoned environment that his body can't fight off.
Perhaps he sacrifices himself to save his friends or Pikachu. For instance, if there was a dangerous situation like a collapsing cave or a powerful attack aimed at his friends, he could put himself in harm's way and not survive.
Obviously, Dark Ash is one of the main characters. He's the center of the story with his transformed state. Serena might also be a main character as she could be trying to reach out to Ash or deal with the new Dark Ash.
In some fanfictions, Ash might die while protecting his Pokémon from a powerful and evil force. He could sacrifice himself to ensure their safety.
The main appeal is their relationship. In the series, they have a special bond. Fanfictions allow fans to explore this bond further, whether it's romantically or as great friends. It gives a chance to see them in new situations not shown in the original series.
One great fanfiction could be 'Ash and Serena's Unseen Adventure'. It might explore their relationship further as they journey through a new region filled with unique Pokemon. Another could be 'Serena's Dream Come True with Ash', where Serena finally achieves her long - held dreams while Ash is right by her side supporting her. And there's also 'The Bond of Ash and Serena', which delves deep into how their bond grew over their adventures.
One possible interesting plotline could be Dark Ash's struggle with his new, darker side while still having memories of his former self. Maybe he has to face off against his old friends who don't recognize him at first.
Team Rocket could also be the focus of a reunion fanfiction. Maybe they've reformed and are having a reunion to celebrate their new lives away from their villainous ways. They could be showing off their new Pokemon or skills that they've developed.
The writing style matters a lot. A great Pokemon XYZ Ash x Reader fanfic uses vivid descriptions to bring the story to life. It makes you feel like you are right there with Ash and the reader. The dialogue should be natural, as if it could actually be something Ash would say in the series. Also, the fanfic should have some emotional depth, whether it's the excitement of a new discovery or the warmth of the relationship between Ash and the reader.
You can try fanfiction websites like FanFiction.net or Archive of Our Own (AO3). They have a large collection of fan - created stories, and you're likely to find 'ash xyz fanfiction' there. Just use their search functions and type in relevant keywords.
There are fanfictions where Ash in the 'ash xyz fanfiction' has to deal with a strange phenomenon in the XYZ region. It could be something like all the Pokemon start acting oddly. In some stories, Ash teams up with an XYZ character who has a unique ability that he's never seen before, and together they explore a mysterious part of the region.
The unique thing about Pokemon XYZ abridged fanfiction is that it often takes the existing story and condenses it while adding new elements. For example, it might focus more on the relationships between the characters.