Naruto could use his Four Tails form to fight a new and powerful enemy that the normal ninja of the Hidden Leaf can't handle. For example, an enemy with the ability to nullify regular chakra attacks.
One great Naruto Three Tails fanfic is 'The Tale of the Three - Tailed Beast's Bond'. It focuses on a young ninja who discovers a unique connection with the Three - Tails. The story is filled with exciting battles and character development as the protagonist tries to understand and control the power of the Three - Tails.
Kabuto could also be a good antagonist. After he gained all those powers and knowledge, he might target Naruto's six - tails form. He could use his medical ninjutsu to try and manipulate Naruto's transformation or even try to extract the power of the six - tails for his own use. Since he has the ability to mimic other ninja's techniques, he could be a formidable foe against Naruto in six - tails form.
One idea could be a story where Naruto has more control over his Four Tails form earlier than in the original series. He could use it to protect the Hidden Leaf in a new and unexpected way, perhaps by combining it with some new jutsu he's created on his own.
A good Naruto Three Tails fanfic often has a strong understanding of the source material. It should accurately portray the nature and abilities of the Three - Tails. For example, it might describe how the Three - Tails' chakra is different from other tailed beasts.
Well, a cool plot for Naruto six - tails form fanfiction might be about time travel. Naruto accidentally travels back in time while in six - tails form. He then has to figure out how to hide his form from his younger self and the people in the past. At the same time, he could use his knowledge from the future and the power of the six - tails to prevent some great disasters from happening in the past, which would change the future in unexpected ways.
No. Fanfiction should be about positive exploration of characters and their stories. Abusing a character like Tails is unethical and not in the spirit of fanfiction.
In some fanfictions, characters like Jiraiya might be involved. He could be researching the Three - Tails Jinchuuriki phenomenon, trying to understand more about the connection between the host and the tailed beast. Tsunade could also make an appearance, especially if there are political aspects related to the Jinchuuriki in the story. For example, she might have to make decisions about how to protect the Jinchuuriki from outside threats while also ensuring the safety of the village.
Character development can be shown through Naruto learning to control the Nine - Tails' power more precisely. For instance, at first, he might struggle and the power might be wild. But as the story progresses, he can gain more finesse, which shows his growth. Another way is his relationship with the Nine - Tails itself. If he starts off seeing it as just a power source and then comes to understand it as a sentient being with its own feelings, that's great development.
A great story idea could be that Naruto's Nine - Tails form gets a new upgrade. Maybe he discovers a hidden ability within the Nine - Tails' chakra. For example, he could gain the ability to create portals to different places in the ninja world only while in the Nine - Tails form. Another idea is that Naruto is forced to fight an enemy who can also take on a form similar to the Nine - Tails. This would lead to an epic battle of power and strategy. Additionally, a fanfiction could focus on the origin of the Nine - Tails form in Naruto's family. Naruto could go on a journey to uncover secrets about his ancestors and how they related to the Nine - Tails.