One possible plot could be that Big Mom somehow ends up in the Naruto world due to a strange rift in dimensions. She then tries to take over the hidden villages, believing them to be new territories for her to rule. Naruto and his friends have to figure out her strange powers and find a way to send her back to her own world.
A plot could involve Big Mom being a long - lost relative of one of the powerful clans in the Naruto world. When she arrives, she stirs up a lot of chaos as she has her own ideas about how things should be run. The clan initially welcomes her, but as her true, tyrannical nature reveals itself, Naruto and his allies have to stop her from causing more destruction within the clan and the village at large.
Maybe Big Mom is reincarnated in the Naruto world as a powerful kunoichi. She retains her memories of her past life and her love for food. She uses her unique devil fruit - like abilities (in a way adapted to the Naruto universe) to become a famous and feared figure. Some ninjas want to use her power for their own gain, while Naruto wants to help her find a new purpose in this new world.
One possible plot implication could be a change in Luffy's power source. Since Big Mom has such unique and powerful abilities, Luffy might inherit or be related to some of those powers in the fanfic. Maybe his Devil Fruit ability could be related to Big Mom's in some way.
One idea could be a story where a grandchild of Big Mom discovers a long - lost family secret that changes their perception of the family's power structure. For example, they find out about a hidden treasure that holds the key to a different kind of power than the one Big Mom wields.
One possible plot could be that the mom character, who is known for her large posterior, has a special lemon tree in her garden. The story could revolve around the family's adventures related to this lemon tree, like making lemonade together and having a family bonding moment over it.
The plot might involve the grandson having a secret heritage that links him to both Kaido and Big Mom. This could be a source of great power, but also a great danger. He might be hunted by other pirates or factions who want to use him for their own gain. In the fanfic, he could start off as an underdog, but gradually grow in strength and influence, all while trying to keep his true identity a secret from Kaido and Big Mom.
Obviously, Naruto and Big Mom would be main characters. Naruto would be the one to oppose Big Mom if she was causing trouble in the Naruto world. His determination and never - give - up attitude would be pitted against Big Mom's powerful and often - cruel nature.
One possible plot could be Naruto being transported to the Claymore world. He might initially struggle to understand the unique rules and the existence of Yoma. But with his ninja skills and never - give - up attitude, he could start training Claymore warriors in new combat techniques, like his shadow clone jutsu. This would change the power dynamics in the Claymore world as they now have a new way to fight Yoma and Awakened Beings.
One possible plot could be that Naruto finds himself in the world of Kenichi and decides to train at the Ryozanpaku dojo. He could bring his unique ninja skills and chakra techniques, which would amaze the masters there. Maybe he'd get into friendly sparring matches with the disciples, teaching them some of his ninja tricks in return for learning their martial arts. This would create a lot of comical and action - packed moments as Naruto's high - energy ninja style clashes with the more traditional martial arts of the Kenichi universe.
A possible interesting plot could be Naruto discovers a hidden ninja village where parkour is the key to unlocking ancient secrets. He has to master new parkour skills to traverse the village's dangerous terrains filled with traps and challenges, all while facing off against a rival ninja group who also wants the secrets.
One possible plot could be Naruto being summoned into the DxD world by some sort of magic accident. He might initially be confused but quickly adapt his ninja skills to the new environment. He could team up with some of the DxD characters to face a common enemy, like a powerful fallen angel or a rogue devil. His Rasengan and shadow clone techniques would be quite unique in this world.
One interesting plot could be Naruto entering a cooking competition in the Hidden Leaf Village. He might use his ninja skills, like speed and precision, to prepare amazing dishes. For example, he could use his shadow clone jutsu to chop ingredients really fast. His unique style of cooking, influenced by his ninja life, would surprise the judges and the other contestants.