One possible plot could be that Riolu is being chased by some bad guys who want to use its power. Ash rescues Riolu and they team up. As they journey, Riolu learns from Ash's kindness and determination. They enter Pokémon battles together, and Riolu's unique fighting style combined with Ash's strategies help them win. Also, their relationship could grow deeper, with Riolu becoming one of Ash's closest Pokémon companions.
Perhaps the fanfiction could have a plot where Ash discovers a Riolu with some special abilities. He has to protect Riolu from those who want to use its powers for bad. This could lead to an adventure filled with battles and new friendships for Ash and Riolu. It might also explore the bond between Ash and Riolu as they grow together. Ash could learn new training techniques from Riolu's unique skills, and Riolu could learn about trust and friendship from Ash. There could be a big showdown at the end against an evil organization that wants to capture Riolu.
The fanfiction could revolve around Ash and Riolu's bond. Since Riolu can sense auras, it might be able to sense Ash's strong will and determination. They could go on an adventure to discover more about Riolu's species and its hidden powers. Along the way, they meet other trainers and Pokémon, and Riolu grows stronger with Ash's guidance.
In another plot, Riolu could be a Pokémon that has been abandoned by its previous trainer. Ash stumbles upon it while on his journey. At first, Riolu is very distrustful of humans, but Ash shows it kindness and patience. Through Ash's training methods and the bond he forms with his other Pokémon, Riolu slowly warms up to him and allows itself to be caught.
Well, the plot could involve Ash's transformation into Riolu being a result of some magical or scientific experiment gone wrong. Maybe he has to adapt to his new form and learn to use Riolu's abilities like Aura Sphere. He might also struggle with being recognized by his friends at first.
Well, perhaps Ash could be magically transformed into a Riolu. He might then struggle to adapt to his new form. For example, he would have to learn to use Riolu's unique moves like Force Palm in a completely different way compared to using his Pokémon attacks as a human. He could also face challenges in communicating with his old Pokémon friends as a Riolu.
Well, it could be about Ash's journey with the Riolu egg. Maybe he has to protect it from various dangers in the wild. He might face off against Team Rocket who are trying to steal the valuable egg. Ash could also learn a lot about Riolu's species while waiting for the egg to hatch, like their natural habitats and behaviors.
Well, it could be about Ash finding a lost Riolu in the forest. Ash decides to take care of Riolu and train it. They go on adventures together, facing different Pokemon battles. Riolu could grow stronger under Ash's guidance and they might aim to win a big Pokemon tournament.
Another possibility is that the shiny Riolu has some special powers that Ash discovers. They could be related to a hidden legend in the Pokemon world. Ash and the Riolu then have to protect this secret from those who would use it for evil. They might travel to ancient ruins and encounter other mysterious Pokemon on this journey.
It could be about Ash finding a Gyarados in an unexpected place, like a hidden lake in a forest. Then he tries to train it and form a bond with it, facing challenges along the way.
One possible plot could be that Ash finds a Riolu as his starter pokemon. Riolu is initially very shy and distrustful of Ash. But as they go on adventures together, Riolu starts to open up. They face challenges like battling against Team Rocket who tries to steal Riolu for its potential power. Ash has to train Riolu not just in battle skills but also in trusting him completely. This journey of building trust and growing stronger together could be a great fanfiction plot.