Well, it depends on the popularity of this particular pairing within the fan community. There might be some fanfics, but it could also be a relatively niche pairing. You could also try reaching out to Pokemon fan groups on social media platforms to ask if anyone knows of such fanfics.
Friendship is a very common theme. Since Mimikyu is often a bit of an outsider and Pikachu is so well - known, many fanfics focus on how they can become friends despite their differences.
Adventure is also a popular theme. They might go on a journey to find a rare item or to rescue a fellow Pokémon. In these fanfics, their relationship grows as they face difficulties during the adventure.
A pikachu x oshawott fanfic might focus on their friendship. They could start off as strangers, perhaps meeting in a Pokemon center. Oshawott might be a bit shy at first, but Pikachu's friendly nature helps break the ice. And as they get to know each other, they form a deep bond that helps them through tough times.
Friendship is a very common theme. Pikachu and Ash have a special bond that is often explored in these fanfics. Their loyalty to each other and how they support one another through different situations.
I'm not sure if there is a specific 'ash no pikachu fanfic' out there. There are countless fanfics in the Pokémon fandom, but this particular one might be hard to find. You could try searching on dedicated fanfic websites like FanFiction.net or Archive of Our Own and use the relevant keywords to see if it exists.
Pikachu might become more empathetic. Usually, Pikachu is known for his energy and courage. But in a fanfic with Buneary, he could learn to understand Buneary's more delicate feelings. For instance, if Buneary is sad because she misses her family, Pikachu could learn to comfort her in his own way, which would make him more in - touch with emotions.
A common theme is friendship. Pikachu and Buneary are often shown as good friends, relying on each other. Another theme could be adventure, as they explore the Pokemon world together.
One possible plot could be that the female ashchu discovers Pikachu has a special power that no one else has noticed. She then embarks on a journey with Pikachu to understand and develop this power, facing various challenges along the way.
I'm not sure specifically about 'female ashchu x pikachu fanfic'. However, there are many Pokémon fanfics out there. You could try searching on fanfic websites like FanFiction.net or Archive of Our Own. Maybe you'll find something related to an interesting female character and Pikachu.