Pikachu is a very likely candidate. It's Ash's most iconic Pokemon and has a deep bond with him. Whenever Ash is in trouble, Pikachu often steps up to protect him.
When starting your 'pokemon ash and pokemon fanfiction', it's important to have a clear goal for your story. Are you trying to show Ash's growth as a trainer? Or maybe explore a new side of the pokemon world? Once you've decided that, think about the other characters you'll include. Will Pikachu have a more prominent role? Or will you introduce new human characters? Develop your setting, whether it's a new region or a familiar place with a new twist, and then start writing the story bit by bit, letting your creativity flow.
Ash could be a Pokémon trainer with a different starting point in this fanfiction. Born in 1987, by 1997 he might have already made a name for himself in local Pokémon battles. He could have a team of Pokémon that he rescued from difficult situations, like a Charmander that was abandoned by its trainer. His story could revolve around giving these Pokémon a second chance and proving that Pokémon don't need to be 'perfect' to be strong.
The impact of Ash's loss in the fanfiction could extend beyond just himself. His Pokémon might also feel demoralized. However, this could also be an opportunity for them to grow stronger together. Ash could start training more intensively, seek new training methods, or even try to catch new Pokémon to strengthen his team.
To write your own, start by creating a conflict. Let's say Ash and a female Squirtle are in a region where water is scarce. This forces them to find new ways to survive and keep Squirtle healthy. You also need to develop their characters. Ash could be more protective of the female Squirtle because of the difficult situation. Write in a way that shows their growth throughout the story.
One interesting plotline could be Ash starting a new adventure in a previously unexplored region. He might encounter new Pokemon species and form unique bonds with them.
There could be a new rival for Ash. This rival might have a very different approach to Pokemon training, like focusing more on the beauty and grace of Pokemon rather than just battle strength.
Well, their life would be full of adventures. They could travel around different regions together, with Misty showing her water - type Pokémon skills and Ash using his battle experience. They might also start a Pokémon training school in Pallet Town, teaching young trainers about Pokémon care and battle strategies.
Well, it could be about Ash having daily adventures with legendary Pokemon. Maybe he stumbles upon a Mew in a forest and they start a friendship. He could learn about the unique powers and personalities of legendaries like Lugia and Ho - Oh in his everyday encounters.
To write your own Ash and Pokemon fanfiction, start by thinking about what you want to change or add to Ash's story. Do you want him to have a different team? Or face a new villain? After that, plan out the story structure. You could have a beginning where Ash discovers something strange, a middle with lots of battles and challenges, and an end where he overcomes all. Also, use vivid descriptions of the Pokemon and the places they visit. For example, describe a dark and spooky forest where Ash has to search for a rare Pokemon. Write in a way that makes the reader feel like they are right there with Ash on his journey.