In the 'harry shows his power fanfic', perhaps it's a story where Harry has to show his power in a wizarding competition. He might use his unique abilities like Parseltongue to outwit his opponents and prove his worth. He could also draw on his connection with the Patronus charm to protect himself and others during the tasks.
There are fanfictions where Naruto's power is shown through his ability to connect with the spirits of past Hokages. With their combined wisdom and his own strength, he's able to perform a super - powerful jutsu that not only protects Konoha but also restores the balance of the ninja world. He uses this new - found power to face an ancient evil that has been awakened.
His rivalry with Goku also contributed to his power growth. Every time Goku achieved a new level of power, Vegeta was pushed to catch up. For example, when Goku became a Super Saiyan God, Vegeta trained hard to reach a similar level of power. This back - and - forth between them led to his continuous improvement in strength.
In this fanfic, Harry is the main character. However, we could also expect to see Dumbledore making an appearance. Dumbledore has always been a guiding figure for Harry, and in a story about Harry showing his power, Dumbledore might offer some wisdom or crucial information. Neville could also be a key character. He has his own growth in the original series, and in this fanfic, he could be inspired by Harry's power and contribute to the overall plot in some way.
Well, Naruto could show Boruto his Sage Mode power. Sage Mode gives Naruto enhanced strength, speed, and the ability to sense chakra more acutely. It's a very powerful form that Naruto has mastered over time. By revealing it to Boruto, he might be teaching Boruto about the different levels of power and the hard work required to achieve such power.
In a fanfic, Naruto might power up by having a spiritual awakening. He could connect with the spirits of past Hokages in a deeper way, gaining their knowledge and some of their power. This could enhance his existing jutsu and give him new abilities. Vegeta could power up if he were to face a near - death experience against Naruto. This could trigger a hidden potential within him, like a new type of Super Saiyan form that has unique abilities. He could also fuse with another Saiyan (if there were another Saiyan available in the fanfic's scenario) to create an even more powerful being.
In fanfictions, Naruto's power growth can be much more rapid. For instance, he might quickly master new jutsu that in the original series would have taken a long time to learn. This is because fanfiction writers often want to show Naruto at his peak or explore different power - up scenarios faster.
The power level would be insanely high. Naruto already has access to a huge amount of chakra, especially in his later forms like Six Paths Sage Mode. Vegeta, on the other hand, has his Super Saiyan forms which multiply his power exponentially. When fused, they would likely have a power level that could easily rival some of the most powerful beings in both universes.
In this fanfiction scenario, Vegeta's power might manifest in Naruto's ki control. Since Vegeta is from the Dragon Ball universe where ki is important, Naruto could start to sense and manipulate a similar type of energy. He could use this newfound energy for things like enhanced speed, allowing him to move so fast that he appears as a blur to his enemies. Also, it could be used for energy blasts, although Naruto would have to learn how to shape and control them in his own ninja - like way.