One way would be through power systems. Naruto's chakra could be related to the magic or power in High School DxD. The fox yokai part could be used to explain some of the more mysterious powers. For example, Naruto's fox - like speed and strength could be seen as yokai - like abilities in the High School DxD world.
To blend the elements, the fanfic could start with a common ground like a shared threat. Let's say a powerful yokai from Naruto's world somehow crosses over to the High School DxD world. Naruto, being part fox - yokai himself, would be drawn into the situation. His skills and knowledge from his own world would be crucial in dealing with this threat. The different races in High School DxD would have to work with Naruto. His relationship with the nine - tailed fox could be explored further in this context, and perhaps his bond with the fox could be a key to unlocking new powers or solutions that involve a combination of the two worlds' elements.
One way is through the power systems. Naruto's chakra could interact with the magic and powers in High School DxD. For instance, a character from High School DxD might be fascinated by Naruto's ability to use chakra and it could be a starting point for a relationship in the mass harem. Another aspect could be the cultures. The shinobi culture of Naruto's world is very different from the high school and supernatural culture of High School DxD. This contrast could create interesting situations in the fanfiction.
Another way to blend the cultures is through their forms of combat. The ninja way of fighting in Naruto, with its emphasis on stealth, agility, and various jutsu, can be compared and contrasted with the more brute - force and magical combat in High School DxD. Characters could learn from each other, like a devil learning Naruto's shadow clone jutsu and using it in their battles. This would not only blend the combat cultures but also create new and exciting battle scenarios.
It could be really exciting. Imagine Naruto's ninja skills combined with the supernatural elements of High School DxD. The fox yokai aspect could add a whole new layer of mystery. Maybe Naruto could be a transfer student in the High School DxD world and his fox - like powers or chakra could be mistaken for some kind of yokai ability. His combat skills would surely make him stand out among the students there.
Well, such a fanfic could be really interesting. It might involve a character who has the abilities or traits from both 'High School DxD' and 'Naruto' universes and is leading the yokai. Maybe this leader could use the ninjutsu from 'Naruto' while also having the devilish powers from 'High School DxD' to rule over the yokai. For example, they could use shadow clones to patrol the yokai territory and at the same time use some sort of demonic charm to keep the yokai in line.
One way is through the power system. The Susanoo's power could be compared or combined with the powers in Highschool DxD. Naruto could bring his ninja way of thinking into the Highschool DxD world. For instance, his idea of never giving up could inspire the Highschool DxD characters. And in terms of the world - building, the fanfic could have Naruto's world of ninjas and the Highschool DxD's world of demons and angels co - exist. The Susanoo could be seen as a new and fearsome power in the Highschool DxD world.
Well, one way it could blend is by having Naruto's ninja skills incorporated into the High School DxD world. Maybe Naruto could use his shadow clone jutsu to create diversions during the Rating Games in DxD. The Ten Tails' power could be a major plot device, like a powerful force that both sides in DxD are trying to either control or prevent from being controlled. For example, some of the devils in DxD might see the Ten Tails as a way to gain ultimate power over the other factions.
One way to blend these elements is through the concept of evolution. In Pokemon, evolution is a key aspect. In the fanfic, this could be linked to Naruto's power - up system. Maybe a Pokemon's evolution could be triggered by a Naruto - style training regime. And the god aspect could be that a certain character has the power to oversee and influence all evolutions in this new world. Also, the Naruto world has different clans with unique abilities. These could be incorporated into the fanfic by having Pokemon associated with specific clans. For instance, the Uchiha clan's Sharingan could be related to a certain type of Psychic - type Pokemon.
A crossover fanfic could explore a leadership where the leader of yokai has to adapt to the different cultures of 'Naruto' and 'High School DxD'. In 'Naruto', loyalty is often based on shared values and a sense of community. In 'High School DxD', it can be more about power and personal charisma. The leader of yokai would need to find a balance. They could introduce concepts like ninja training to the yokai from 'Naruto' to make them stronger, while also using the more modern and flashy elements from 'High School DxD' to make the yokai more appealing to other factions in both universes. This would help in establishing their leadership over the yokai.
If we consider a Naruto and Jessica Rabbit fanfic, their worlds could blend in a number of ways. For instance, Naruto's world has chakra, which is a form of energy. Jessica Rabbit's world has a certain kind of magic or allure. They could find that these two forms of power have some similarities. Maybe they could combine their powers to defeat a common enemy. Naruto could use his shadow clone jutsu, and Jessica could use her charm to distract the enemy while the clones attack.
A possible blend in the fanfiction could be through a magical or technological device. Maybe a scientist in Highschool DxD creates a device that can open portals to other universes, and Naruto's world is one of the destinations. When Naruto arrives, he discovers that there are elements related to Beelzebub there. The device could malfunction and start to merge the three universes in unexpected ways. This would force the characters to adapt to the new situation, with Naruto using his ninja training to survive, the Highschool DxD characters using their social and magical skills, and those related to Beelzebub using their demonic powers to deal with the chaos.