One possible plot could be that the Jewel of Life has been stolen from its rightful place. Arceus chooses a young and brave Pokémon or human to retrieve it. Along the way, the protagonist discovers the true nature and power of the jewel and has to face many challenges, like traversing dangerous terrains and outsmarting cunning enemies.
Maybe an ancient Pokémon that has been in slumber for ages wakes up and realizes the importance of the Jewel of Life. So, it becomes the main character and embarks on a journey to safeguard it. This Pokémon could have unique powers that help it in this mission.
The plot could be about Blu, Leaves, Jewel, and Rio going on a secret mission to save their part of the jungle from an unknown threat. Maybe there's a new villain that's causing trouble for the birds and their habitat.
One possible plot could be that fem Arceus somehow ends up in the Harry Potter universe. Maybe she's drawn there by the powerful magic. She could then use her unique abilities to help Harry and his friends in their fight against Voldemort, like using her power to heal the injured or to create barriers against dark magic.
Well, perhaps Naruto could be transported to the world of Arceus. He might discover his own chakra has some unique connection to the power of Arceus. Maybe he has to team up with Pokémon to fight against some dark forces that are threatening both the Pokémon world and his own ninja 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.
Well, it could be about Mewtwo, a powerful psychic Pokémon, and Arceus, the creator Pokémon, having a battle of wits. Maybe Mewtwo challenges Arceus' authority in the Pokémon world, leading to an epic showdown where their powers clash and the very fabric of the Pokémon universe is at stake.
One possible plot could be that Ash discovers a threat to the Pokémon world that only Arceus can stop. But Arceus is somehow corrupted or misinformed. So Ash has to fight Arceus to snap it out of it and save the world.
Well, it could be that Ash makes a discovery that goes against Arceus' grand plan and is thus betrayed. Maybe he finds out something about the balance of the Pokemon world that Arceus doesn't want known.
Well, it could be that Arceus, being a powerful and god - like Pokémon, sees Naruto's potential and decides to take him under his wing. Maybe Arceus helps Naruto gain new powers related to Pokémon abilities. For example, Naruto could learn to use Pokémon moves in his battles against the Akatsuki or other enemies in the Naruto world.
In this fanfiction, it might show Naruto being able to communicate with Pokémon like Arceus can. He could use this ability to gain allies in the form of Pokémon. His friends in the Naruto world might be initially skeptical or even afraid of his new connection. But as the story progresses, they learn to accept it and work together with Naruto and his Pokémon allies to face greater threats that are endangering both the Naruto world and the Pokémon world.