One plotline could be that his sister is being controlled by an enemy. Naruto has to fight her to break the control. He uses his Nine - Tails chakra to overpower her and then uses his talk - no - jutsu to bring her back to her senses, thus defeating her in a sense.
Perhaps Naruto's sister challenges him for the title of Hokage. In the ensuing battle, Naruto shows her that his experience and his connection with the village are far stronger. He uses his Shadow Clones to outmaneuver her and his Rasenshuriken to prove his superiority in combat, resulting in her defeat.
One possible plotline could be that Lemon has some unique ninja abilities that Naruto discovers, and they train together to become stronger. Maybe she has a special chakra nature that Naruto has never seen before, and they figure out how to use it in combat.
A plotline might involve Naruto starting to act out in negative ways to get his parents' attention. He could start getting into trouble at school or in the village. Maybe he would start to explore his own powers in secret, away from his family, and discover some unique abilities that he then uses to show his parents what they've been missing. Also, there could be a plotline where Naruto tries to build a relationship with his sister in secret, hoping that through her, he can get closer to his parents.
One plotline could be that Lemon discovers a hidden power within herself that is related to an ancient Uzumaki clan secret. As she tries to master this power, she has to keep it a secret from the wrong people in the village who might misuse it. Along the way, she gets help from unexpected allies like Shikamaru, who uses his intelligence to guide her in understanding the power better.
Well, one way could be if Naruto has some new, super - powerful jutsu that he's developed. Maybe he's found a way to combine his Sage Mode with his Nine - Tails chakra in a completely new and unexpected way that gives him an edge over Hashirama.
Perhaps she has a special connection to an ancient and powerful ninja art. This could lead to her being targeted by some villains who want to use her for their own gain. Naruto then has to step up to protect his sister, and in the process, they both learn more about their family's past and their own powers.
One possible plotline could be that Naruto's sister secretly helps him during his difficult times in the village. Maybe she provides him with extra training resources or helps him outwit the bullies without him knowing it's her at first.
Well, in a fanfic anything can be possible. Naruto has his own set of powerful jutsu like the Rasengan and Shadow Clone Jutsu. The Justice League members also have their unique powers. But if the writer of the fanfic wants Naruto to win, they can create scenarios where Naruto's speed, strategy, and chakra powers outwit the JL. For example, Naruto could use his clones to confuse Superman while using a Rasengan to take him out. Then he could use his shadow clones to distract Batman and use his chakra control to disable Cyborg's systems. It really depends on how the fanfic is written.
One possible plotline could be that Kurama, as Naruto's sister, helps him secretly in his battles. Since she is a powerful being, she might use her chakra to boost Naruto's strength without others knowing, adding an interesting dynamic to his fights against powerful foes.
Another plot could be that she was raised in a different village under false pretenses, believing she was an orphan. When she discovers she is Naruto's sister, she has to decide whether to stay in the village she grew up in or return to Konoha. Along the way, she has to face her own identity crisis and deal with the political implications of her new - found family relation.
One possible plotline could be that Lee's sister, who might be a kunoichi in training, catches Neji's eye during a sparring session. Neji, initially reserved, starts to become more interested in her as he sees her determination and unique fighting style. They could then start to train together secretly, and their relationship slowly blossoms into a deep friendship with a hint of something more romantic as they face various challenges in the ninja world.