Some potential rivals could be the local Unova trainers who are known for their unique battling styles. For example, a trainer who specializes in using Bug - type Pokemon could be a tough rival for them.
One possible plot could be that Ash and Dawn explore Unova together, facing new Pokemon and trainers. They might encounter a rare Pokemon that is causing trouble in the region and work together to solve the problem.
In this fanfiction, Ash and Dawn's adventures in Unova could be filled with new Pokemon encounters. Ash might bring his typical enthusiasm and determination, while Dawn could add her own unique charm and Contest skills. They could team up to face new challenges, like strong Gym Leaders in Unova. Their friendship would also likely develop further as they explore this new region together.
In this fanfiction, they may face a new villainous team in Unova. This team could be causing trouble for the local Pokemon and trainers. Ash and Dawn would have to use their combined skills to stop them. Ash's battle skills and Dawn's ability to think on her feet during Contests would be valuable assets.
There are fanfictions where Ash and Dawn participate in Unova's Pokémon contests. Dawn, with her contest experience, could teach Ash some new tricks. They could enter as a duo and create unique performances using Unova's Pokémon. In some fanfictions, they also meet old friends from other regions in Unova, which leads to a lot of fun interactions and reminiscing about their previous adventures.
It could be a Team Plasma - like organization that is causing trouble in Unova. They might be trying to steal Pokémon or disrupt the balance in the region, and Ash and May have to stop them.
In such a fanfiction, Ash and May could encounter new and rare Pokemon in Unova. They might face tough battles against powerful trainers and gym leaders. For example, Ash could use his Pikachu in unique strategies against Unova's electric - type Pokemon that have different abilities compared to those in other regions.
There could be a new, unknown group of villains in the fanfiction. They might be after a special type of Pokemon that is native to Unova. These villains could be using underhanded tactics to catch these Pokemon, and Ash and May would have to uncover their motives and stop them. For instance, they could be trying to use the power of these Pokemon for their own selfish gains, like taking over Unova's Pokemon centers or disrupting the Pokemon league.
The theme of discovery is quite common. Ash discovers new Pokemon species, new battle strategies, and new aspects of the Unova region. There's also the theme of competition, as he battles against various trainers in Unova. His interactions with these trainers and how he learns from each battle is a key part of many fanfictions.
In Unova - based fanfiction, if Ash gets involved with dragons, it could be an amazing story. Maybe he befriends a baby dragon Pokémon that has been separated from its family. Ash then has to protect it from poachers or other dangerous Pokémon. Along the way, he forms a strong bond with the dragon, and this bond could change his approach to Pokémon training completely. He might start to focus more on the emotional connection with his Pokémon rather than just battle strategies.