A great plot could be that Team Dim Sun has a new, powerful weapon or Pokémon that they plan to use to take over the region. Ash, with his experience and determination, has to find a way to stop them. He could go on a journey to discover an ancient Pokémon or a secret power that can counter Team Dim Sun's new threat.
Maybe in the fanfiction, Ash teams up with some unlikely allies to take on Team Dim Sun. This could include Pokémon that are usually not seen working together. They could combine their strengths to defeat Team Dim Sun's devious plans.
Obviously, Ash is one of the main characters. He's the protagonist who will be facing off against Team Dim Sun.
There could be a fanfiction where Team Rocket finally manages to steal all of Ash's Pokémon. But instead of using them for evil, they realize the strong bond between Ash and his Pokémon and start to have a change of heart. This would be a great exploration of the themes of redemption and the power of friendship in the context of the Ash vs Team Rocket dynamic.
One idea could be a friendly competition between Dawn and Serena over who can help Ash catch the most rare Pokémon in a new region. They might set different strategies and use their unique skills to outdo each other while still remaining friends.
One interesting plot idea could be Ash and Lillie going on a special mission together to find a rare and powerful Pokemon that has the ability to heal other Pokemon. They face many challenges along the way, like rough terrains and other trainers who also want to capture this Pokemon. Another could be a story where Lillie gets lost in an unknown part of the Alola region and Ash has to use all his skills and knowledge to find her. During this time, he discovers more about Lillie's past and the secrets she has been hiding.
One idea could be that Ash gets transformed into a Pokémon and has to figure out how to communicate with his friends. Another could be that Team Rocket manages to use a new device to transform Pikachu into a different type of Pokémon. Maybe Ash and Team Rocket end up having to team up when a new, more powerful villain emerges who wants to transform all Pokémon into mindless servants.
One idea could be that Ash, as the leader of Team Rocket, uses his knowledge of Pokémon in a new way. He might focus on stealing rare Pokémon not just for evil purposes but to prove a point about Pokémon training ethics. For example, he could target trainers who mistreat their Pokémon and then 'liberate' the Pokémon into a better environment he creates. Another plot could involve Ash leading Team Rocket in a new direction of cooperation with other Pokémon organizations. Instead of always being the bad guys, they could form alliances to solve some of the more complex problems in the Pokémon world, like dealing with a new, powerful and dangerous Pokémon species that threatens the balance of nature.
Another interesting concept for an Ash vs Evil Dead crossover fanfiction is to introduce a new villain that is a combination of different evil forces from both the movies and the show. This super - villain could be immune to some of Ash's usual tactics, forcing him to team up with unlikely allies. The fanfiction could explore how they figure out the villain's weaknesses and ultimately defeat it. It could also include some comical moments, like Ash's one - liners in the face of danger.
One idea could be exploring the backstories of the characters more deeply. Maybe a story about their childhood and how it shaped their relationship as brothers.
Maybe there is a new character, a brilliant scientist, who has developed a dangerous weapon. Shi - Jin and Mo - Yeon have to team up with their friends to stop this weapon from being used, while also dealing with the scientist's personal vendetta against the military. This would add a lot of action and suspense to the fanfiction.
One idea could be that they all end up in a shared dreamscape created by Freddy. In this space, Jason and Michael have to team up to fight Freddy's mind games and try to escape while also dealing with their own instincts to battle each other. Another could be that a powerful sorcerer summons them all to a modern city and they start wreaking havoc, and a group of brave humans try to use their knowledge of each slasher's weaknesses to stop them.