His Pikachu would probably be very supportive. It would stay by his side as he studies, maybe even help him in small ways like fetching medical tools. It trusts Ash completely and would be happy to see him pursue something new.
One key element could be Ash's character development. In such fanfictions, he might face new and tougher challenges that push him to grow even more as a trainer. Another element could be the introduction of rare or new Pokemon species. It would be exciting to see Ash interact with Pokemon we haven't seen him with in the original series. Also, his relationships with his friends, like Misty and Brock, might be explored in new and deeper ways, adding more emotional depth to the story.
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.
In the fanfic, Ash could enter a major coordinator competition where he faces off against some of the toughest opponents. He might struggle at first because he's used to traditional Pokemon battles. But as the competition progresses, he starts to understand the nuances of coordinator battles better. His friends could also play important roles, like Misty giving him advice on how to make his Pokemon's water - based attacks look more appealing, and Brock helping with Pokemon health and grooming to ensure they look their best during the shows.
Maybe Ash discovers a hidden power within himself that is linked to the legendary Pokemon. This power could be awakened through a series of dangerous adventures, like facing off against an evil team that is trying to capture all the legendaries. As he progresses, he gradually transforms into a being with some of the abilities of a legendary Pokemon.
There could be a rogue legendary Pokemon that sees Ash's transformation as a threat to the natural order. This legendary Pokemon, with its own set of motives, could be trying to prevent Ash from becoming a fully - fledged legendary - like being. It might set up various obstacles and battles for Ash, testing his will and strength at every turn.
Well, perhaps Ash starts to idolize Pikachu after seeing its unique powers in a battle. He might try to imitate Pikachu's moves and even start collecting Pikachu - themed items.
In the 'pokemon ash becomes a charmander fanfiction', it could be that Ash witnesses a Charmander perform an incredibly heroic act. For example, saving a group of Pokemon from a dangerous situation. This act of selflessness and courage makes Ash look at Charmander in a whole new light. He starts to study Charmander's behavior, training techniques specific to Charmander, and even starts collecting Charmander - related items. He becomes so obsessed that he starts to model his whole Pokemon - training approach around what he has learned from Charmander.
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.
Perhaps the story could involve Ash being transformed into a Pokémon through some magical or scientific experiment gone wrong. As a Pokémon, he would join a group of other Pokémon on a journey. He might face challenges like being hunted by Pokémon hunters or having to prove himself to a Pokémon tribe. Along the way, he'd also learn about the different perspectives of Pokémon in their own world.