There could be a flying monster with razor - sharp claws. This kind of monster can swoop down on villages unexpectedly, making it a fearsome adversary for the ninja. It would force the ninja to develop new strategies to deal with aerial threats.
Often, Naruto himself is one of the main characters facing these monsters. His determination and powerful jutsu make him a natural choice to take on such threats.
In a fanfiction, the aliens could capture Naruto and try to study his unique abilities. The monsters then decide to rescue him because they realize his powers could be the key to defeating the aliens once and for all. The story could involve a lot of action as the monsters infiltrate the alien base to save Naruto.
A giant, hulking beast - type duel monster could also be very powerful. It might have incredible strength and endurance, able to take on multiple enemies at once. Its sheer physical presence could intimidate opponents, and it could use its brute force to smash through defenses and deal massive damage.
I'm not entirely sure as I haven't read this specific fanfiction. But it might be a story that combines the Naruto universe with elements of 'king of monsters' in a unique way. It could be about Naruto having some sort of encounter or adventure related to the 'king of monsters' concept.
In the 'Naruto Father of Monsters' fanfiction, perhaps Naruto discovers he has an ancient bloodline that is connected to some mythical monsters. This newfound connection could put him at odds with the Hidden Villages as they fear the power he might unleash. He then has to fight to protect his new family of'monsters' while also trying to keep the peace in the ninja world. It could also involve him teaching his'monster' children the ways of the ninja, which would be really interesting to read about.
One common theme is self - improvement. As Naruto hunts monsters, he often has to learn new skills and overcome his own limitations. Another theme is friendship. He might team up with others, and their relationships grow stronger through the shared experience of monster hunting.
Sasuke could be one of his main allies. Despite their past differences, they could put aside their issues to support Naruto in his role as the King of Monsters. Sasuke's powerful combat skills would be a great asset in battles against those who oppose Naruto.
Well, it could change the power dynamics completely. If Naruto can summon duel monsters, he might have an extra edge in battles. For example, against strong opponents like Pain or Madara. He could use the monsters' unique abilities to turn the tide of the fight, which would make the plot more unpredictable as his enemies would have to deal with not just Naruto but also his summoned monsters.
The main antagonists could be some of the traditional ninja clans who see Naruto's connection to the monsters as a threat to their power structure. They might fear that the monsters will disrupt the balance of power in the ninja world.