It could be a group of Team Rocket - like villains. They are after the unique powers that the reborn pokemon might possess. Since the reborn pokemon has a human - like intelligence, they see it as a valuable asset to use for their evil plans, like stealing all the precious pokemon resources or taking over a certain region.
One idea could be the main character being reborn as a Pikachu and having to navigate the world with its electric powers while making friends with other pokemon. Another could be being reborn as a Eevee and having the unique ability to evolve into any form at will, which causes both envy and admiration among other pokemon. Maybe the reborn pokemon has memories of being a human and uses that knowledge to outwit trainers and other threats.
One great Amaria fanfiction in Pokemon Reborn is 'Amaria's Adventure'. It delves into her backstory more deeply, showing her journey before she was known in the game. It has some really interesting character development for her.
A possible fanfiction could involve Tyranitar being a powerful protector in the Pokemon Reborn world and Rattata being an unexpected ally. Maybe Rattata has some unique ability that Tyranitar discovers during a battle against a common enemy, and they form an unbreakable bond as a result.
Well, perhaps a plot where Naruto is reborn as a Pokemon trainer and has to start from scratch. He might face challenges like dealing with powerful Gym Leaders while still trying to figure out how the Pokemon world works. His determination from his past life as Naruto could help him overcome difficulties and he might even train his Pokemon in a ninja - like way.
Obviously Naruto would be the main character since it's about him being reborn as a Pokemon fan. His Pokemon partners could also be considered main characters. For example, a Pikachu that he befriends early on and they go on adventures together.
Amaria is a really interesting character in Pokemon Reborn. Fanfictions about her allow us to explore her character more deeply. For example, we can see different sides of her personality that might not be fully shown in the game.
In a fanfiction, Tyranitar and Rattata might interact in a comical way. Rattata could be constantly trying to steal Tyranitar's food, and Tyranitar would be frustrated but also amused. This could lead to a series of adventures where they end up working together to find better food sources or protect their stash from other Pokemon.
The story of Pokemon Reborn can be lengthy. If you're thorough and take your time to enjoy all aspects of the game, it could take you more than 30 hours. But if you just focus on the main quests, it could be shorter, maybe 15-20 hours.