Sasuke could be an important character. He might be initially confused and a bit annoyed by Naruto's cat - like behavior, but as the story progresses, he could start to find it endearing or even useful. Another character could be Kakashi. He would probably be the one trying to figure out what caused Naruto to act this way and how to reverse it, if needed.
Gaara could be involved too. Since he has his own unique relationship with Naruto, he might be one of the few people who can understand Naruto's new form on a deeper level. Maybe he has some knowledge about strange transformations from his own experiences in Suna. And Sakura, she could be the one trying to use her medical ninjutsu to figure out if there's any physical or mental change in Naruto that's causing him to act like a cat.
Bulbasaur - girl might be a great choice too. Her connection with nature and plant - based attacks could add an interesting dynamic. She could help Naruto understand the Pokemon world better, especially when it comes to things like finding herbs or dealing with forest - related challenges. There could also be a fiery - tempered Charmander - girl who provides a contrast to Naruto's more easy - going nature and has her own set of powerful fire - type attacks.
In the 'naruto acts like a cat fanfiction', a plot could be that Naruto befriends a group of stray cats in the village. They teach him their ways, and he in turn, protects them from the meaner villagers. As he acts more like a cat, he starts to understand their language, sort of like a telepathic connection. This connection helps him gather intelligence from all the places the cats can go, which he then uses in his ninja duties. This would be an interesting way to show Naruto's kind heart and his ability to adapt to new situations.
There could also be some side characters. For example, Kakashi might notice Naruto's strange behavior and try to figure out what's going on. And maybe some of the female characters in the village would befriend Naruto in his 'girl' form and introduce him to different aspects of being a girl, like shopping for kunoichi gear or sharing girl - talk.
Obviously, the Jedi who adopt Naruto would be main characters. For example, a Jedi Master like Obi - Wan Kenobi could be the one to discover Naruto and take him under his wing. Another could be Yoda, who would be very interested in Naruto's unique abilities and would play a role in his training. There could also be other young Jedi trainees who become Naruto's friends or rivals during his time at the Jedi temple.
Sasuke could be one of the main characters. He might initially be skeptical about Naruto's new identity but then come to accept it and fight alongside him. Sakura could also be there, perhaps using her medical skills to help Naruto when he gets injured during his adventures related to his Pegasus heritage.
One of the main characters could be Fleur Delacour. Since she's from Beauxbatons, she might be the one to first interact with Naruto. She could be curious about his strange abilities and help him adjust to the school. Another could be a male student at Beauxbatons who is initially jealous of Naruto getting all the attention but later becomes his friend after seeing his true character.
There could be a leader of the horde. This character might be initially skeptical of Naruto but later comes to respect him. Another character could be a young member of the horde who looks up to Naruto as a role model and wants to learn from him.
Maybe there are new characters created specifically for this fanfiction. They could be local inhabitants of the wet area, such as a water nymph - like character who has knowledge about the secrets of the place and either helps or hinders Naruto's journey.
Lelouch could be a main character. Since he is a key figure in the Code Geass world which has Britannia. He and Naruto might start as rivals due to their different approaches to justice but later become allies. Suzaku could also be involved. He might be initially suspicious of Naruto but come to respect him as Naruto shows his good intentions in the Britannian world.
Hinata could be one of the main characters. She might support Naruto in his efforts to rebuild the Whirlpool Village, both morally and with her Byakugan skills which could be useful for scouting and security.