The anti - venom concept can be unique in Naruto fanfiction by making it related to the tailed beasts. For example, the chakra of one of the tailed beasts could be the key to creating an anti - venom. Naruto, being a jinchuriki, could then use this connection to save someone from a venomous attack.
A unique way could be to have the Kyuubi's chakra be tied to the bikini. For example, the more powerful the Kyuubi's chakra, the more elaborate and magical the bikini becomes. Naruto has to learn to control this new aspect of the Kyuubi's power as they go on a journey to save the village from a new threat. This would add a fresh twist to the typical Naruto and Kyuubi relationship.
You could have a character who is an atheist suddenly experience a moment of 'by the grace of God'. For instance, they are about to be killed by a powerful supernatural being, and then a mysterious force saves them. They then start to question their beliefs and explore the role of God in the Supernatural world. It would add an interesting character arc.
Another unique way is to have an Incubus be the key to unlocking a hidden power within Naruto. Maybe the Incubus has a special connection to an ancient and forgotten power source in the Naruto world. When Naruto encounters the Incubus, it sets off a chain of events that leads to him accessing this new power, which is different from his normal Sage Mode or other known powers.
You could make it so that a character from the Fullmetal Alchemist universe ends up in the Naruto world and teaches Naruto and his friends fire alchemy. This would lead to some interesting cultural clashes and exchanges. They could combine the principles of alchemy with chakra control in ways that are completely unexpected, like creating new types of ninja tools using alchemical transmutation.
The Fruit Loops could be part of a magical prank. A new ghost in town uses Fruit Loops to create illusions all over the place. Danny has to deal with these illusions while also trying to figure out who is behind it all. He might initially think it's just a normal human prankster, but then realizes it's a ghost with a strange sense of humor. The Fruit Loops could be the source of the illusion - creating power, and Danny has to find a way to stop the flow of their magic.
A unique incorporation could be through a time - travel aspect. Imagine a character from the future traveling back to the Pokemon Sun and Moon era while pregnant. Their knowledge of future Pokemon and events could be intertwined with their pregnancy journey. They might be trying to protect their unborn child from future threats that are related to the Pokemon world. Or perhaps they are on a mission to ensure a certain Pokemon evolution or event happens so that their child will grow up in a better Pokemon - related future.
One unique way is to make the dragon fire act as a form of communication. Imagine a dragon that can send messages through the patterns of its fire. In the fanfiction, the main character has to learn to decipher these messages to solve a mystery or prevent a disaster. Another idea is to have the dragon fire be a source of time - travel. When the fire engulfs a certain magical object, it can send the holder back in time, leading to all sorts of interesting plot twists in the Harry Potter universe.
You could make the heritage potion a key part of a mystery. Maybe it's the only thing that can solve a series of strange disappearances in the wizarding world. The characters have to track down the ingredients, which are scattered across different magical locations, and then brew the potion correctly. Along the way, they learn about different family heritages and how they might be connected to the mystery.
You could make the tempest a form of chakra corruption. For example, an evil ninja creates a device that distorts chakra and it causes a tempest of chaotic energy. Naruto discovers this and has to find a way to purify the chakra and stop the tempest. This would add a new aspect to the Naruto universe's power system.
The concept of 'barbarian' can be incorporated by changing Naruto's setting. Instead of the normal ninja villages, he could be in a more primitive land. For instance, he might be in a place where there are no advanced ninja tools, so he has to rely on his raw skills and strength like a barbarian would.