One idea could be the six - tails jinchuriki's struggle to control the power. For example, they constantly have to battle the inner urge of the six - tails to go on a rampage. Another plot could involve the jinchuriki being hunted by an evil organization that wants to extract the six - tails' power for their own malicious use. They would then have to fight and outwit this organization while also dealing with the social ostracism that often comes with being a jinchuriki.
A cool plot could be the six - tails jinchuriki forming an unlikely alliance with other jinchurikis to protect the ninja world from a greater threat. Maybe they start off distrusting each other because of their different tailed beasts, but as they face the common enemy, they learn to work together and even become friends. Or perhaps the jinchuriki discovers a hidden ability of the six - tails that has been long forgotten and uses it to save their village from a powerful enemy attack.
One idea could be exploring the relationship between the 2 - Tails Jinchuriki and the other Jinchuriki in the Naruto world. Maybe they form an alliance to protect themselves from those who would use their power for evil.
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.
Well, a plot could revolve around the jinchuriki's journey to understand and control his newfound harem. He might face challenges like jealousy among the harem members. For example, some might feel that he spends more time with one than the others. Also, the harem could be from different villages, and the jinchuriki has to deal with the politics involved in having a multi - village harem. He could also discover that there is a prophecy related to his harem and his role as a jinchuriki.
One interesting story could be about the two - tails jinchuriki's journey to control the beast's power. Maybe they face a powerful enemy and have to learn to use the two - tails' abilities in a new way to defeat them.
Sakura could be a great choice. She has strong medical ninjutsu skills and a no - nonsense attitude. She could help the six - tails jinchuriki when they get injured during battles against the power of the six - tails or external enemies. Also, her growth as a character could be further explored as she tries to understand and support the jinchuriki.
One idea could be exploring the origin of the Ten - Tails in a different light. Maybe it was created by an ancient civilization for a noble purpose that got corrupted over time. Another could be a story where a young ninja discovers a hidden power within the Ten - Tails and has to learn to control it without being consumed by its dark energy.
One possible plot idea could be the Jinchuriki's struggle to control the power of the Five Tails Gobi. Maybe they face challenges from other ninja clans who want to use the power for their own gain. Another idea is that the Jinchuriki has to go on a journey to find a way to fully merge with the Five Tails without losing their own identity. And perhaps they form an unexpected alliance with a group of outcasts in the ninja world to protect the Five Tails from a greater threat.
Perhaps in the fanfiction, the Zero Tails is a manifestation of the negative emotions of the ninja world as a whole. A group of young ninjas discover this and they try to find a way to purify the Zero Tails. They seek the help of old sages and learn ancient jutsu to attempt this purification, which could lead to a battle against those who want to keep the Zero Tails as a weapon of mass destruction.
One idea could be Naruto having a unique connection with the Nine Tails that allows him to access new forms not in the original series. For example, a form that combines his human features with more fox - like aspects in a more aesthetically pleasing and powerful way.
One idea could be exploring the Four Tails' backstory more in - depth. Maybe it has a connection to an ancient ninja clan that was long forgotten. Another is a story where the host of the Four Tails has to team up with an unexpected ally to control its power.