One interesting plotline could be the protagonist's first encounter with a rare Unova Pokemon. It might be a unique take on how they bond and start their journey together.
I'm not sure specifically as there could be many different plots in this fanfiction. It might involve the adventures of the trainer in the Kalos region, encounters with new Pokemon, and the journey to become a Pokemon master.
Since it's a fanfiction about Pokemon in the Alola region, it could involve the main character exploring different islands. They might take part in the island challenges, meet unique Alola Pokemon forms, and have interactions with the local characters. For example, they could team up with Hau or Lillie to battle Team Skull or discover some hidden secrets in the Alola region's beautiful landscapes.
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.
I don't know for sure as it's a fanfiction. But it could be a young trainer, perhaps based on the player character in the games. Maybe there are also some unique NPCs created by the fanfiction author.
I don't know for sure without reading it, but probably the trainer who is on the Alola journey, and maybe some of the well - known Alola characters like Hau or Lillie.
One great fanfiction could be 'Ash's Unova Redemption'. It focuses on Ash making up for his past losses in Unova and really developing his skills further. It has some unique battles and character interactions that make it stand out.