In this fanfiction, it's possible that Ash's immortality causes him to explore the very essence of the Pokémon world. He could delve into the mysteries of the Pokémon universe, like the origin of the Legendary Pokémon. Since he has all the time in the world, he might also be involved in epic battles against ancient and powerful foes that no ordinary trainer could face. His immortality gives the author a chance to rewrite the boundaries of the Pokémon adventure.
One interesting idea could be Ash's eternal journey through different regions. He might encounter new and unique Pokémon that are long extinct in normal timelines. Another idea could be his relationships with other characters over an infinite span of time. For example, how his friendships with Brock and Misty evolve and change in ways that are not possible in the original storyline.
One interesting idea could be Naruto exploring eternal life while still protecting the Hidden Leaf. He might face new challenges as he outlives his friends and has to deal with the loneliness that comes with immortality.
Another idea is Ash starting with a Bulbasaur. His journey could focus more on nature and plant - type Pokemon evolution. He might get involved in more environmental - related plots, like helping sick plants in the forest with Bulbasaur's powers.
One idea could be Ash getting a special upgrade to his Mega Buster that allows him to shoot different types of elemental blasts. For example, fire blasts to defeat ice - type enemies more easily.
Another plot idea is that Chikorita falls ill in a new region Ash is exploring. Ash has to search for a rare herb to cure it. During this time, he meets other trainers who either help or hinder his search. This plot would focus on Ash's determination to save his Pokémon friend and the relationships he forms during the search.
One plot idea could be that Ash and Android 21 team up to fight a common enemy in a tournament. Another could be a story where Android 21 tries to understand human emotions through Ash's experiences. Or perhaps a plot where they travel through different dimensions together.
Some plot ideas might include Ash and Hoopa teaming up to rescue a group of Pokémon that have been captured by an evil organization. Hoopa could use its portals to get into the enemy's lair. Another plot could be that Hoopa gets sick, and Ash has to find a way to heal it. He travels far and wide, meeting different Pokémon and people who might have the cure. And there could be a story where Hoopa reveals a hidden world to Ash, a world full of ancient Pokémon and secrets. Ash then has to explore this world with Hoopa and make sure these secrets don't fall into the wrong hands.
A more heart - warming plot could be Riolu being initially afraid of its own strength and Ash helping it to gain confidence. Maybe Riolu accidentally causes some damage and is scared of using its power again. Ash then trains with it in a special way to show Riolu that its strength can be used for good. This could involve some cute and touching moments between the two as they build a stronger bond.
One idea could be that the ash aura tree is a magical entity in a fantasy world. It could be the source of power for a group of heroes. They have to protect it from dark forces who want to use its power for evil. Another idea is that the tree has a sentient spirit within it that can communicate with a chosen individual, guiding them on a journey of self - discovery.
One idea could be focusing on how Ash's friends react to the news. They might be shocked at first but then rally around to support her. Another could be Ash dealing with the physical and emotional changes during pregnancy while still trying to pursue her goals.
Well, perhaps in the 'ash in a dress fanfiction', Ash is forced to wear a dress as a punishment by a mischievous Pokemon. This leads to him having to learn new ways of moving and interacting while in the dress. He could also end up starting a new trend among the Pokemon, where they all want to wear dresses like him for fun.