In the fanfiction, perhaps there's a plot where Ash has to save a legendary pokemon from an evil organization. He might use his experience and the trust of his other pokemon to rescue it. This would not only show his courage but also how much he values all pokemon, whether they're common or legendary.
Another possible plotline is that a legendary pokemon chooses Ash as its trainer. This could be because it sees something special in him, like his unwavering determination. Then they embark on a journey to discover the secrets of the pokemon world that are only known to the legendaries, which would be full of mystery and excitement.
One possible plotline could be Ash's discovery of his own latent legendary powers. Maybe he starts to exhibit abilities that are unique to legendary Pokemon, like controlling the weather or having an extraordinary bond with all types of Pokemon.
In some 'legendary pokemon and ash fanfiction', there might be a plotline where Ash travels to a hidden realm where only legendary pokemon exist. Here, he has to prove himself worthy to the legendary pokemon in order to gain their help in his journey to become a pokemon master. This could involve facing various trials and challenges that test his skills, courage, and friendship with his pokemon.
One possible plotline could be that Ash has to overcome his own self - doubt. He might initially think he's not worthy of catching a legendary pokemon. But through his journey, he discovers his hidden strengths and forms a deep bond with the legendary pokemon. For example, he could learn that his pure heart and unwavering determination are what attract the legendary pokemon to him.
One interesting plot could be Ash forming an unbreakable bond with a Legendary Pokemon. Maybe he helps the Legendary in a time of crisis, like saving it from an evil organization. This would lead to the Legendary choosing to stay by Ash's side and help him in his battles and adventures.
Another possible plotline could be that Evil Ash is on a quest to conquer a certain region. Serena, with her own Pokemon, decides to oppose him. Along the way, they both discover new things about the Pokemon world and themselves. Serena might have to team up with other trainers to stand a chance against Ash's newfound power.
Obviously, Ash is one of the main characters. He's the protagonist who has a passion for pokemon and is always eager to become a pokemon master. And the legendary pokemon he encounters or befriends would also be important characters. For instance, if it's Lugia, Lugia would play a major role in the story as it's a very powerful and mysterious pokemon.
One common plotline is that Ash is chosen by a legendary pokemon for a special mission. For example, he might be chosen by Lugia to stop an evil organization from misusing the power of the sea. Another is that Ash stumbles upon a legendary pokemon in a hidden or dangerous place, like in a long - lost ancient ruin, and forms a bond with it.
One interesting plotline could be Ash facing a new and extremely powerful legendary Pokemon that challenges his skills as a champion in ways he's never experienced before. This could lead to him having to develop new battle strategies.
One interesting plotline could be Ash becoming a super powerful trainer overnight in the fanfiction. Maybe he discovers a new type of Pokemon power that gives him an edge in battles.
One interesting plotline could be Mallow and Ash going on a special cooking adventure where they combine their skills. Mallow's cooking knowledge and Ash's love for Pokémon could lead them to discover a new Pokémon that is attracted to Mallow's special dishes. They might then have to figure out how to catch it while also dealing with some challenges from Team Rocket who want to steal the Pokémon for themselves.