The relationship between Naruto and Bulma would be really fascinating. Since they are from two very different worlds, seeing how they interact, fall in love, and build a family would be a major plot point. Also, how Naruto would train Trunks in his own ninja - like way while Trunks also has his Saiyan powers would add a lot of depth to the story.
Another interesting aspect could be the reaction of the other characters in both universes. How would Goku react to Naruto being Trunks' dad? And what about Sasuke or the other ninja in Naruto's world? The clash of different cultures and power systems from the two universes would surely create a lot of drama and interesting plot developments in this fanfiction.
In many Naruto and Saw fanfictions, one interesting plot point is seeing how Naruto's ninja skills are used to survive Saw - like traps. For example, his shadow clone jutsu could be used to test or bypass certain deadly mechanisms. Another is the clash of ideologies. Naruto stands for friendship and perseverance, while Saw's world is often about moral lessons through extreme pain and suffering. So, how Naruto's positive values would deal with the negative and cruel concepts of Saw makes for a great plot point.
The relationship development between Naruto and Tashigi is also a major plot point. Since they come from different backgrounds, seeing how they gradually understand and respect each other is fascinating. Some fanfictions show their relationship evolving from initial distrust or misunderstanding to a deep friendship or even a romantic relationship, with all the ups and downs and emotional moments in between.
Another interesting plot point is the cultural exchange between their worlds. Saber comes from a world of knights and magic, while Naruto is from a ninja - dominated world. In some fanfics, they teach each other about their respective cultures, like Saber showing Naruto the concept of chivalry and Naruto introducing Saber to ninja stealth techniques.
Well, one interesting plot point is when the power systems cross over. For instance, Naruto's ability to use chakra and the zombies' unique powers in iZombie. Maybe a zombie gains the ability to use chakra or Naruto has to face off against a zombie - like enemy that has powers similar to his opponents in his own world.
The cultural clash between Naruto's world and Gilgamesh's origin is also a great plot point. Naruto comes from a world of ninjas and hidden villages, while Gilgamesh has a more ancient, myth - based background. Their different values and beliefs often lead to interesting dialogues and situations, like when they discuss leadership or the concept of heroism.
One interesting plot point is when Naruto uses his Rasengan in Middle - earth battles. It's a completely different world from his own, and seeing how this powerful ninja technique fares against the likes of goblins and trolls is exciting.
The combination of powers is also really cool. Picture a character from Naruto using their elemental jutsu in combination with Watch Dogs' hacking to take down an enemy. Maybe they hack into a security system and then use a fire jutsu to create chaos. It makes for some really exciting and unexpected battle scenes. Also, some fanfictions explore how the ninjas' stealth and combat skills can be enhanced or hindered by the modern technology of Watch Dogs.
Another plot point could be the exploration of new worlds. If Naruto characters travel to the 'To Love Ru' universe, they would encounter all sorts of strange and wonderful things. How they adapt to this new environment, make new friends or enemies, and find their place in this different world can be a great source of plot development. There could also be a reverse situation where 'To Love Ru' characters end up in the Naruto universe and have to deal with ninjas and shinobi politics.
In many 'naruto hitman reborn fanfiction', the idea of a character from one world ending up in the other is a big plot point. Imagine Naruto waking up in the world of Hitman Reborn or Tsuna finding himself in the Hidden Leaf Village. They have to adapt to new rules, new enemies, and new friends. Also, the way the power systems of both universes interact, like how chakra and the Dying Will Flames could be used together or against each other, is really cool.
One interesting plot point is the power exchange. For example, in some fanfics, Naruto's jutsu are used by Vox Machina members, creating unique combat scenarios. Another is the culture clash. Naruto's shinobi culture meeting Vox Machina's more medieval - like fantasy culture can lead to some humorous and thought - provoking moments.