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.
Definitely. The idea of Ash and Pikachu's friendship is very popular in fanfiction. Their relationship is iconic. Fanfictions could tell stories of how they first met and how that initial connection grew into an unbreakable bond. It could also include side characters from the Pokémon world who notice and are inspired by their friendship, like Misty or Brock seeing how Ash and Pikachu always have each other's backs.
In a fanfiction, Ash and Pikachu could enter a Pokemon contest where the theme is lemons. Pikachu has to use its skills in a creative way related to lemons. Ash trains Pikachu hard, and they come up with a unique performance where Pikachu zaps lemons to create a spectacular light show. This earns them high marks from the judges and they make new friends among the other contestants.
One possible reason could be that Ash senses a dangerous situation where Pikachu's full power might attract unwanted attention or put them in more danger. For example, if there are powerful and unseen enemies nearby, Ash might hold Pikachu back to keep a low profile.
Common themes include the power of teamwork. Ash and Pikachu work together so well, and fanfiction shows how their combined efforts can achieve great things. The theme of perseverance is also there. They don't give up easily in their quests, whether it's winning a Pokémon league or saving a friend. Additionally, the theme of the Pokémon world itself, with all its unique features, cultures, and rules, is often explored in Ash and Pikachu fanfiction.
One common theme is friendship. The unbreakable bond between Ash and Pikachu is often explored in different ways, like facing challenges that test their friendship. For example, a story might have Pikachu getting sick and Ash going to great lengths to find a cure.
One interesting fanfiction could be about Pikachu getting lost in a mysterious forest and Ash having to use all his skills and the bond they share to find it. He might meet new Pokémon along the way and have to overcome various challenges just to get his beloved Pikachu back.
One possible plot could be that Ash starts his journey with a different starter Pokémon, like Bulbasaur. Without Pikachu by his side, he might face different challenges and form different relationships. He could struggle more in the early battles without Pikachu's electric power, but then develop unique strategies with his new Pokémon team.
There is no such official or acceptable fanfiction. Pikachu is a Pokémon and Ash is a human character, and such a concept goes against the nature of the Pokémon world and is also inappropriate and unethical.
Growth is also a theme. Ash is constantly growing as a Pokémon trainer, and in fanfictions, this growth can be depicted in different ways. Maybe he learns new training techniques with Pikachu's help, or he overcomes personal fears that were holding him back in his journey.