A possible plot is that the female Shukaku is captured by an evil organization. Naruto, being the hero he is, sets out on a rescue mission. Along the way, he discovers more about the female Shukaku's past and her connection to the history of the ninja world. This could involve ancient secrets and prophecies related to the tailed beasts.
One idea could be that the female Shukaku has been living in hiding among the Leaf Village. Naruto discovers her secret and they form an unlikely bond as they train together to control her Shukaku powers. This bond then turns into a deep friendship that might lead to more as they face various threats to the village.
One idea could be exploring the relationship between the Jinchuuriki and Shukaku in more depth. Maybe the Jinchuuriki tries to communicate with Shukaku in a different way than in the original series, leading to new powers or understandings. Another plot could involve the Jinchuuriki being targeted by a new group who wants to use Shukaku's power for their own evil purposes. The Jinchuuriki then has to fight not only to protect themselves but also to keep Shukaku from being misused.
One plot idea could be a crossover where the female Kyuubi and female Shukaku are somehow transported to the FF7 world. They could team up with the FF7 characters to fight a common enemy, perhaps a new threat created by a combination of Naruto -verse and FF7 -verse magic or technology.
One idea could be that Shukaku is somehow transported into the Harry Potter universe. Maybe he ends up in the Forbidden Forest and has to navigate the magical creatures there. Another could be a story where a Hogwarts student discovers a way to summon Shukaku during a particularly difficult time at school, like when facing a powerful dark wizard. Or perhaps Shukaku's powers are combined with a Hogwarts spell to create a new form of magic.
A great plot could involve the female Naruto being sent on a diplomatic mission to another village. There, she discovers a conspiracy against the Hidden Leaf Village and has to use her wits and ninja skills to expose it and prevent a war. Along the way, she also forms unexpected friendships with some of the villagers from the other village, which helps her in her mission.
One interesting Naruto Shukaku fanfiction could be about Shukaku's backstory before being sealed into Gaara. It might explore how it lived in the desert and its interactions with other beings there.
Well, it could be about Naruto having the powers of Shukaku in addition to his own. Maybe he has to learn to control this new power source and face new enemies who are after his unique abilities.
Well, for a Naruto and female shinigami fanfiction, a plot could involve a female shinigami who is an outcast in her own realm because she believes in a different way of handling souls. She crosses into the Naruto universe and meets Naruto. They bond over their shared experiences of being different. Naruto could learn about the afterlife and the concept of souls from her. And she could learn about chakra and the ninja way. Also, perhaps there's a dark force in the Naruto world that is related to a corrupted form of soul - handling, and the female shinigami's knowledge helps Naruto combat it.
One idea could be a female Naruto who has a special ability related to healing. She could use this to not only heal her friends in the Hidden Leaf Village but also to try and bridge the gap between different ninja clans. For example, she might use her healing powers to save a member of a rival clan during a battle, which would then lead to a series of events where the two clans start to cooperate more.
One plot idea could be that a female Akatsuki member is secretly in love with Naruto but is conflicted because of her loyalty to the Akatsuki. She might find herself in situations where she has to choose between helping Naruto or following the Akatsuki's orders. Another idea is that Naruto tries to redeem a female Akatsuki member. He believes in the good in her and tries to convince her to leave the Akatsuki and join the side of the village. A third plot could involve a female Akatsuki member being sent on a mission to spy on Naruto, but ends up befriending him and seeing a different perspective on the world.