He could develop more patience. Since rare pokemon are often hard to find and catch, he would need to wait for the right moment. This could also teach him to be more observant of his surroundings and the behavior of pokemon. And his bond with his existing pokemon could also strengthen as they work together to catch the rare one.
Ash may develop a new sense of responsibility. A rare pokemon is a precious find, and he would need to take good care of it. This could lead to him learning more about different types of pokemon care, and he might also start to think more about the balance of the pokemon ecosystem. He would understand that catching a pokemon is not just about having it in his collection, but also about protecting it and its kind.
Well, it could be about Ash traveling to a remote area, like a hidden forest or a mysterious island where the rare pokemon is rumored to live. He might face many challenges on his way there, like tough terrains or other aggressive pokemon. Then, when he finally encounters the rare pokemon, it could be a really intense battle where he has to use all his skills and knowledge of pokemon to catch it.
Ash could become more responsible as he has a unique starter that might need special care or training. He'd have to learn new ways to bond with it, which would make him more empathetic towards Pokemon in general. For example, if the starter is shy, Ash would have to be patient and gentle, thus developing his patience.
Often, in 'pokemon ash and harem fanfic', Ash becomes more confident. With the support of the characters in his harem, he might take on tougher challenges. For example, if a girl in the harem is really good at a certain type of Pokémon battle, Ash could learn from her and become better at that too.
His confidence could grow in a different way. Usually, Ash is confident in battles, but this time, when he catches these rare Pokémon, he might gain confidence in his ability to understand and bond with Pokémon that are very different from the ones he's used to. He could start to see himself as a more well - rounded Pokémon trainer, not just one who battles but also one who can form deep connections with all kinds of Pokémon.
Often, it starts with Ash having an internal struggle or realization about his gender identity. He might notice that he doesn't feel like he fits the traditional male role he has been in. Then, he begins to explore this new side of himself, perhaps trying out different appearances or behaviors that are more in line with his true self.
Ash would likely become more open - minded. Meeting a shiny ghost pokemon at the start would expose him to a type of pokemon he might not have expected so early. This could make him less fearful of the unknown in general. For example, he would be more willing to explore spooky places or deal with pokemon that have a reputation for being difficult to handle.
The fanfiction might focus on how Ash discovers the unique habits and weaknesses of the rare pokemon. He could meet some new friends or rivals along the way who also have their eyes on the same pokemon. And in the end, through determination and his bond with his pokemon, he manages to catch it.
At first, Meloetta might be shy around Ash. But as Ash shows kindness and respect for Meloetta's power and uniqueness, they start to bond. Ash could take Meloetta to different Pokemon contests or battles. Meloetta, in turn, uses its music to cheer on Ash's Pokemon. Over time, they become inseparable friends, relying on each other in tough situations and having fun together during their travels.
A fanfic could be centered around Ash exploring a new region where Mimikyu is said to be very common. Ash is eager to add a new and different Pokemon to his team. He meets a local trainer who tells him all about Mimikyu's habits. Ash follows the trainer's advice and goes to a particular meadow where Mimikyu likes to play. He waits patiently until he sees a Mimikyu. Ash then uses his best Pokeball and with a little bit of luck, catches Mimikyu. Once caught, he discovers that Mimikyu has some hidden powers that he's excited to explore and train with.
Ash often becomes more confident in these fanfictions. He learns new ways to communicate with his Pokemon during contests, which makes him a better trainer.