One possible plot could be that Torchic is a special, rare variant that has unique powers. Ash, with his determination, helps Torchic unlock these powers while they face off against powerful new villains in the Pokémon world. They could go on a journey to find a way to fully control these powers and in the process, make new friends and discover new Pokémon species.
Well, another option could be to check out Pokémon - centered forums. Some fans might share their own written fanfictions in those places, or at least be able to point you in the right direction for finding ones where Ash has Torchic from the start. These forums are often a great community for Pokémon enthusiasts to exchange ideas and works.
One possible plot could be that Ash discovers a lost Axew in a mysterious forest. The Axew is scared and alone, and Ash decides to take it under his wing. Together, they embark on a journey to find Axew's family. Along the way, they face various challenges like battling other Pokémon and traversing difficult terrains. Ash uses his experience and Pikachu's help to protect Axew.
Perhaps it's a story where Ash and Froakie form an even deeper bond than in the original series. They might go on a quest to find a rare Pokemon that only Froakie can sense, and along the way, Ash learns more about Froakie's past and its potential. Froakie could also teach Ash some new strategies in battles that help him become a better trainer overall.
The plot might involve Ash starting his journey all over again, but this time with a Charizard as his very first Pokémon. Since Charizard is a powerful and somewhat stubborn Pokémon, Ash would have to learn how to handle it right from the start. He could face challenges like other trainers trying to steal Charizard because of its rarity. Ash would have to prove his worth as a trainer and his connection with Charizard to keep it by his side.
Well, it could be about Ash starting his journey with a Ralts. Maybe Ralts is a special one that has unique powers. Ash and Ralts could go through various gym battles together, with Ralts evolving at crucial moments to help Ash win. They might also face some tough opponents who are after Ralts' power.
The plot might involve Ash's Dratini evolving quickly due to their unique connection. It could also have elements of Ash trying to prove that Dratini can be a very powerful Pokémon from the start. He might enter it into Pokémon contests and battles, showing off its unique moves and abilities.
The fanfiction could revolve around Ash and Riolu's bond. Since Riolu can sense auras, it might be able to sense Ash's strong will and determination. They could go on an adventure to discover more about Riolu's species and its hidden powers. Along the way, they meet other trainers and Pokémon, and Riolu grows stronger with Ash's guidance.
Well, the plot might be that Ash stumbles upon a lost Togepi. Since Ash has a kind heart, he takes it under his wing. They then embark on a journey where Togepi starts to show some extraordinary powers that no one has ever seen before. This attracts the attention of Team Rocket who try to capture it. Ash and his friends have to come up with clever plans to outwit Team Rocket every time they make an attempt.
One possible plot could be that Ash, instead of starting with Pikachu in the Alola region, starts with Litten. Litten could be a difficult Pokémon to train at first, but Ash's determination helps him bond with it. They could go on adventures in Alola, facing Team Skull together and Litten evolving as they overcome various challenges.
One possible plot could be that Ash finds Charmander much earlier than in the original series. They could form a really strong bond quickly and start training in a different way. Maybe they focus more on speed and stealth rather than the usual battling approach at first.