One interesting idea could be Naruto getting the power of flight from another fictional universe. It would completely change his combat style and how he moves around the Hidden Leaf Village. Another idea might be Naruto having the power to control time, like being able to slow down or speed up time during battles. This would give him a huge advantage against his enemies.
One idea could be a fanfic where a fembot develops real emotions. Maybe she gets damaged during a mission and while being repaired, some sort of glitch occurs that makes her start to feel things like love or friendship. She could then struggle with her new - found emotions and her original programming as a fembot.
Well, perhaps Harry could have the power of elemental magic. For example, he could control fire, water, air, and earth, which would make his battles against Voldemort even more epic. He could also have the power of healing magic that is so strong it can even revive the dead, but this would come with great moral dilemmas. He might have to decide whether to use this power and disrupt the natural order of life and death.
A plot idea could be that a new character with smoke powers emerges and is initially feared because people don't understand their abilities. But as the story progresses, they use their powers for good, like rescuing villagers from fires by using the smoke to absorb the heat.
One idea could be a story where Naruto discovers a new, hidden aspect of his shadow powers that allows him to communicate with the shadows of the past ninjas. He could learn ancient techniques from them and use this knowledge to defeat a powerful new enemy.
Perhaps his powers are related to some kind of enhanced senses. He could use this to detect threats before they become obvious. This would add a new layer to his character as he becomes more of a 'guardian' figure in the fanfiction.
Perhaps Hiccup has the power to transform into a dragon himself. He could be a half - human, half - dragon hybrid. This would give him the ability to fly faster and fight more effectively against enemies. He would have to hide this power from most of the people on Berk at first because they might not understand. As he learns to control this transformation, he discovers new aspects of the dragon world and his place in it. This power could also bring some internal conflict as he struggles with his human and dragon sides.
One idea could be that Danny discovers the power to manipulate time on a small scale. He can freeze or slow down time for a few seconds to gain an advantage in battles. For example, when facing a powerful enemy, he freezes time to analyze the situation and plan his attack. Another idea is the power of energy absorption. Danny could absorb different types of energy like electricity or fire and use it to boost his own powers or create new attacks. He might absorb the electricity from a power line during a fight in the city and then release it as a powerful electric blast.
One plot idea could be that Naruto discovers his ice powers during a mission in a frozen tundra. He has to learn to control them quickly to survive against the enemies there. Another idea is that an enemy uses a dark jutsu on Naruto that gives him ice powers but also tries to corrupt him. Naruto has to fight against the corruption while learning to use his new powers for good.
In some fanfictions, Spider - Man might gain the ability to teleport across the cosmos. This could lead to him exploring different galaxies and encountering alien species that are both friendly and hostile. He could use his spider - sense in new ways, like detecting threats from across the universe.