One idea could be a story where the protagonist is a time - traveler sent back to the era of Arceus to prevent a great disaster that could wipe out all Pokemon in the future. They have to team up with ancient Pokemon trainers and figure out how to communicate with Arceus to stop it.
A possible plot for a Pokemon Ash and Arceus fanfiction could be that Ash is summoned by Arceus to a sacred place. There, Arceus reveals that Ash has been chosen to help balance the powers of all the different types of Pokemon in the world. This would involve Ash traveling to different regions and facing challenges related to each type of Pokemon. For example, in a region dominated by fire - type Pokemon, he might have to find a way to cool things down without harming the Pokemon. Another plot could be that Ash accidentally angers Arceus, and as a punishment, he has to go on a journey to prove his worth and respect for all Pokemon. He has to complete tasks like helping a group of endangered Pokemon species thrive again. And, a third plot idea is that Arceus gives Ash the ability to transform into different Pokemon forms for a short time to better understand them, and Ash uses this power to solve various problems in the Pokemon world.
One idea could be a story about a trainer who discovers a hidden power within Arceus that has been lost for centuries. This power could be the key to saving the Hisui region from a new, unknown threat.
One idea could be a story where a young trainer discovers a hidden connection between Giratina and Arceus. Maybe they accidentally stumble upon an ancient relic that has the power to summon both of them. The trainer then has to navigate the complex relationship between these two powerful Pokemon, trying to prevent a great disaster that would occur if they were to battle in the human world.
A fun plot could be Arceus crossing over into a world of magic like in the Harry Potter universe. It could be a strange and interesting encounter as Arceus, a powerful Pokémon god, enters Hogwarts. The students and professors would be both amazed and a bit scared perhaps. And Arceus would have to navigate this world of spells and wizards while also trying to find a way back to its own realm.
One interesting plot point could be how Ash's training methods change under Arceus's influence. Since Arceus is a powerful and divine Pokémon, it might introduce Ash to new and unique ways of training his Pokémon that are different from what he's used to. This could lead to his Pokémon evolving in unexpected ways or developing new and powerful moves.
One interesting plot could be Naruto being transported to the world of Arceus and having to learn about the Pokémon there while still retaining his ninja skills. He could use his jutsu in new and creative ways to interact with Pokémon.
Well, one interesting aspect could be the unique interpretations of Arceus in the fanfiction. Writers might explore different powers or backstories for this powerful Pokémon that we don't see in the official games. Another aspect could be the creative settings they create. For example, they could place Arceus in a completely new region or situation. Also, the relationships between Arceus and other Pokémon or characters in the fanfiction can be really engaging, showing new dynamics that add to the overall allure of the Pokémon world.
Another plot could involve a trainer who discovers a strange connection between Arceus and a mysterious diaper - like artifact. As they explore this connection, they find out that it has something to do with an ancient power that was sealed away long ago. The trainer then has to protect Arceus and the artifact from evil forces who want to use this power for their own gain.
One idea could be the main character being reborn as a Pikachu and having to navigate the world with its electric powers while making friends with other pokemon. Another could be being reborn as a Eevee and having the unique ability to evolve into any form at will, which causes both envy and admiration among other pokemon. Maybe the reborn pokemon has memories of being a human and uses that knowledge to outwit trainers and other threats.
One idea could be a story where a young trainer discovers they have a special connection with Arceus. They embark on a journey to understand this bond and along the way, they face challenges from other trainers who are jealous of their unique relationship.