It's debatable. There are many strong fictional characters, and it depends on various factors like powers, abilities, and the context of their stories.
I think Zeno would be a really tough opponent. Zeno has the power to erase entire universes, and a Goku and Goku Black fusion, despite being extremely powerful, would have a hard time against such a being with god - like powers.
Goku's ultimate form in the manga is Ultra Instinct. This state grants him enhanced combat abilities and reflexes. It's a breakthrough that showcases his potential and is a key factor in his toughest battles.
Well, the King Kamehameha story is quite interesting. King Kamehameha started his journey to unify the islands at a time when the Hawaiian archipelago was divided among many chiefs. He was able to amass an army and navy, with the help of some Western advisors and weapons. He first conquered the Big Island of Hawaii. Then he gradually expanded his territory to the other islands. His leadership led to the creation of a more cohesive Hawaiian nation. His legacy can be seen in the modern - day Hawaiian culture, language, and governance.
It's really hard to say. Goku has the power to destroy planets and reach incredible levels of strength with his Super Saiyan forms. However, Naruto has the power of the tailed beasts and his own sage mode which gives him a huge boost in power. And Sonic, while he may not have the raw power like the other two in terms of destruction, his speed is so great that he could potentially outmaneuver both of them. So it really depends on the situation and how the author writes it.
In the King Kamehameha story, his early life and upbringing within a noble family was a starting point. Then, his realization of the need to unify the islands led to him gathering resources and allies. His battles against rival chiefs on different islands, like Maui and Oahu, were key events. These battles were often fierce and required strategic thinking. His successful unification not only brought political stability but also influenced cultural exchange and development within the Hawaiian islands. For example, trade between the islands became more organized and new cultural elements were introduced as a result of the unified nation he created.
The combination of two very different universes. Naruto has its own complex ninja world with unique powers and characters, and the Kamehameha is a super - powerful move from Dragon Ball. When these two are mashed up in a fanfic, it creates a new and exciting dynamic.
I'm not sure of a specific 'naruto kamehameha fanfic' off - hand. But you can try searching on fanfiction websites like FanFiction.net or Archive of Our Own. They usually have a wide variety of fan - created stories that might include what you're looking for.