In some fanfics, a plot twist could be that the villain in the Naruto world is somehow related to the problems in the Happy Feet world. For example, Orochimaru might be the one causing the fish shortage in the penguins' world. It completely changes the dynamic as Naruto has to not only deal with his own world's issues but also those of the penguins.
A really unexpected plot twist could be that the entire Naruto universe is a dream of one of the penguins in Happy Feet. So all of Naruto's adventures, his friends, his battles are just a figment of the penguin's imagination. And as the penguin wakes up, Naruto starts to fade away. It makes the reader question the reality of both worlds and the nature of the crossover.
Another interesting plot twist is when the penguins gain chakra. Imagine Mumble suddenly being able to use ninjutsu like the Rasengan. It turns the whole story upside down as the penguins now have the power to fight back against their enemies in a completely different way. This also makes for some really cool battle scenes between the penguins and the Naruto villains.
In some fanfictions, a big plot twist is when Naruto suddenly gains a Devil Fruit ability, completely changing the power dynamics. For example, in 'Naruto's Devil Fruit Adventure', he gets a powerful fruit that makes his ninja skills even more formidable.
Perhaps a plot twist where an evil force is manipulating both their universes and they are the only ones who can see the signs. Naruto and Caulifla must put aside their differences and combine their powers in a way no one thought possible to stop this greater evil that threatens both their worlds and the fabric of reality itself.
Well, there's a fanfiction called 'Kyuubi's True Form'. The plot twist here is that the Kyuubi has a completely different true form than what was expected, and this form has different powers and a different relationship with Naruto. Also, in 'Naruto's Lost Kyuubi', Naruto suddenly loses the Kyuubi for an unexpected reason, like a time - travel accident, and he has to find a way to get it back without his usual power source.
One interesting plot twist could be when Naruto's friends turn against him because they fear the power of the lightsaber he wields. It changes the whole dynamic of their relationships.
In some fanfictions, like 'The Secret Alliance', there's a plot twist where Naruto and Kenichi form an unexpected alliance against a common enemy that was thought to be an ally. It completely changes the dynamic of the story.
In some fanfictions, the plot twist could be that the dinosaurs are actually from another dimension sent to the Naruto world to test the ninja. And Naruto is the only one who can communicate with them because of his special chakra. This leads to him having to form an alliance with the dinosaurs to save the world from a greater threat. It's a really unique way of bringing the two concepts together.
Perhaps Madara fakes his death in the fanfiction after meeting Naruto. Naruto then has to deal with the chaos that follows as Madara secretly manipulates events from the shadows. Or, it could be that Naruto's presence causes Madara to have a change of heart, but then the ninja world doesn't believe that Madara has truly changed and they both have to fight against the world's distrust. There are so many ways the plot can take an unexpected turn in this kind of fanfiction.
One really cool plot twist is when the values of the Naruto universe start to influence the Decepticons in unexpected ways. For example, the concept of friendship and loyalty that Naruto and his friends uphold might start to make some Decepticons question their own motives and allegiances, which leads to a whole new set of conflicts and resolutions in the fanfiction story. This not only adds depth to the story but also makes for a very engaging read as it challenges the typical Decepticon - like behavior we are used to in the original Transformers franchise.
Maybe. It could be that Naruto's friends turn against him because they fear his new Human Torch powers. That would be a big plot twist.
A possible plot twist could be that Naruto's blindness was actually caused by an enemy's secret jutsu that was meant to be permanent, but it turns out that Naruto's Uzumaki bloodline has a hidden ability that can reverse the blindness under certain conditions. This would add an element of mystery and hope to the story.