One possibility is that Ash discovers a young Rayquaza at the start of his journey. Maybe it's injured and Ash nurses it back to health. This could lead to a strong bond between them, and Rayquaza could become his most powerful Pokémon, helping him in battles against tough opponents like Team Rocket or other powerful trainers.
Perhaps in the fanfiction, Ash stumbles upon a mysterious place where he finds a Rayquaza that is being held captive. He decides to free it and in return, Rayquaza chooses to follow Ash. Their adventure together could involve exploring ancient Pokémon ruins, where Rayquaza's powers are needed to unlock secrets and Ash has to learn how to communicate and work with such a powerful Pokémon.
Ash would likely become more confident with a Rayquaza as his starter. Having such a powerful Pokémon would give him an edge in battles, and he'd grow in his leadership skills as he commands Rayquaza. He might also become more responsible, knowing that he has to take care of such a rare and strong Pokémon.
One possible plot could be that Ash hears rumors of Rayquaza's appearance in a far - off region. He sets out on a journey with his Pokémon friends. Along the way, he has to face various challenges and other trainers who also want to catch Rayquaza. Eventually, he uses his unique bond with his Pokémon and his strategic skills to outwit Rayquaza and catch it.
Yes, there are likely 'Ash Catches Rayquaza' fanfictions out there. Fanfiction writers often create stories based on popular Pokémon concepts like Ash catching a rare and powerful Pokémon like Rayquaza. You can try searching on fanfiction websites such as FanFiction.net or Archive of Our Own to find such stories.
The plot could involve Ash and Chimchar facing a series of challenges in a new Pokémon league. They might encounter a powerful villain who has a special device that can nullify Chimchar's fire attacks. Ash then has to find a way to train Chimchar to use its other skills, like its speed and agility, to defeat the villain's Pokémon.
One possible scenario in this fanfiction could be that Ash's journey takes a completely different turn with Latios as his starter. Latios, being a powerful and intelligent Pokémon, might help Ash quickly gain a reputation in the Pokémon world. They could form a unique bond, different from what Ash has had with his other Pokémon in the original series. Ash could use Latios' speed and psychic abilities to his advantage in battles, making him a formidable trainer right from the start.
The plot could start with Ash getting Riolu as his starter Pokémon instead of Pikachu. Riolu might be a bit of a troublemaker at first, not fully understanding Ash's commands. But as they journey together, they start to understand each other better.
One possible plot could be that Ash, instead of starting with Pikachu, starts with a Gastly. Gastly could use its spooky abilities to help Ash in battles. For example, it could use its ability to turn invisible to surprise opponents. It might also play pranks on Ash's rivals, like making them think they're seeing ghosts in the forest where they're camping.
Well, one possible plot could be that Female Ash starts her journey with a Datini. Maybe she discovers Datini has some unique abilities that set them apart from other starters. They could face challenges in the first gym battle together, with Datini using its speed to dodge attacks and Female Ash coming up with creative strategies.
The plot could involve the female Ash and her Dratini exploring new regions not seen in the original series. They could discover ancient Pokémon secrets. For example, Dratini might lead Ash to a hidden cave filled with rare dragon - type Pokémon. Ash has to learn how to train Dratini in a way that suits its unique abilities. Maybe she focuses on Dratini's speed and special attacks rather than brute force. This journey of discovery and growth would be the main focus of the fanfiction.
In this fanfiction, perhaps Ash starts with a Eevee. Since Eevee can evolve into multiple forms, it would add a whole new dimension to his journey. He could face different challenges as he tries to decide which evolution path to take for Eevee, and it would also attract different kinds of Pokémon opponents.