Perhaps he could have the superpower of shape - shifting into different Pokemon forms. This would not only be a really cool power but also very useful in various situations. He could turn into a flying type Pokemon to reach inaccessible places quickly, or a water type to swim underwater and explore the underwater world of Pokemon.
Misty could be another sidekick. She's strong - willed and has her own set of skills. She could use her water - based Pokemon to assist Ash in battles, especially against fire - type opponents. Plus, her knowledge of Pokemon and the world around them could be really helpful in their superhero adventures.
He could have a Froakie. It's a common and cute starter in Kalos. Maybe also a Skiddo for traveling across the Kalos landscapes. And a Bunnelby would be a nice addition for its digging abilities.
It could be a Pikachu. Since Pikachu is often associated with Ash and could be considered a special kind of 'first' pokemon for him in a different take of 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.
Ash could have adventures like exploring a hidden part of the school that has a connection to a rare Pokemon. Maybe there's an old library in the school that holds secrets about legendary Pokemon, and Ash stumbles upon it during a game of hide - and - seek with his new friends.
The other trainers in Pallet Town might look up to him even more now. They could gather around him, asking for stories about his battles and the rare Pokémon he's encountered. It would be a great opportunity for Ash to pass on his experience.
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.
She might have a Bulbasaur. It's a classic starter Pokemon and it could symbolize a connection to Ash's early days as a trainer. Also, Bulbasaur can be very strong and useful in battles as well as contests with its cute appearance.
A Charmander could be a great choice. It's a classic and powerful Pokemon. She could raise it from a small, timid lizard to a strong Charizard. This would mirror Ash's own growth with his Pokemon. Also, it would give her a strong partner for battles and adventures. And it could have a special bond with her, similar to how Ash's Pokemon had with him.
It could be an Eevee. Eevee is a very common yet special Pokemon. It has the potential to evolve into many different forms, so it would be an interesting addition to Fem Ash's team.