If Ash becomes a legendary Pokemon in a fanfic, it would change the whole Pokemon world dynamic. He might be hunted by evil organizations who want to use his power. On the other hand, he could also use his new form to protect the Pokemon world better than ever. His friends would likely have a mix of reactions, from being amazed to being worried about losing the old Ash.
Another possibility is Ash becoming Lugia. Lugia is known as the guardian of the seas. As Lugia, Ash could explore the deep oceans, discover new species of Pokemon, and safeguard the marine ecosystem. He could use his psychic and flying abilities to interact with both water - and flying - type Pokemon, bringing a new era of harmony between different Pokemon types.
Well, if Ash turns into a legendary Pokemon, he'd likely gain a whole new set of powers. For example, if he becomes Arceus, he'd have the power to create and shape the Pokemon world. He could create new Pokemon species or even reshape the existing regions. His friends would probably be both in awe and a bit scared at first. But Ash, being Ash, would still have his kind heart and would use his powers for good.
In Ash's adventures in legendary Pokemon fanfics, he often has extraordinary encounters. For example, he might form unique bonds with legendary Pokemon that are not part of the main canon. These fanfics can take his story in new and exciting directions, like having him team up with a Mewtwo in a way that defies the normal Pokemon - trainer relationship. It's all about exploring the untapped potential of his character in the context of the amazing world of legendary Pokemon.
His confidence might increase a great deal. Since legendary Pokemon are often seen as very powerful, Ash in his new form would feel more capable. He might become more solitary too, as some legendary Pokemon are known to be lone creatures.
One idea could be that Kagome's transformation into a Legendary Pokemon is a result of a strange encounter with a powerful Pokemon artifact in the Pokemon world. Maybe she was exploring an ancient ruin and accidentally activated a spell that merged her with the essence of a Legendary Pokemon, like Mew. This could lead to her having unique powers and abilities that no other trainer has.
One great Ash x Legendary Pokemon fanfic is 'A Bond Beyond Time'. It features Ash forming a unique connection with a Legendary like Mewtwo. The story has exciting battles and explores the idea of trust between Ash and the powerful Legendary.
One popular 'Ash Catches Legendary Pokemon' fanfic is 'The Legendary Bond'. In this fanfic, Ash has a series of encounters with different legendary Pokemon that are really exciting. It shows his growth and determination in a new light. Another good one could be 'Ash and the Legendary Quest' which focuses on Ash's journey to find and catch multiple legendaries across different regions. The way the author describes the battles and the relationships Ash forms with the legendaries is really engaging.
The appeal lies in seeing Ash in new and exciting situations. With legendaries involved, his journey becomes more epic. It's like taking the underdog story of Ash in the anime and supercharging it.
In Ash-centered legendary Pokemon fanfiction, often Ash has extraordinary adventures. He might form unique bonds with legendary Pokemon that are not seen in the official storylines. For example, he could befriend a Mewtwo and together they face off against an evil organization trying to clone more powerful Pokemon. These fanfictions allow for a lot of creativity, expanding on Ash's character and his relationships in the Pokemon world.