There could be a rival ninja clan that has a long - standing feud with the Laguz. They view the Laguz as inferior beings and want to either subjugate them or drive them out of their territory. Naruto has to stand up against this clan and their old - fashioned and cruel ways of dealing with the Laguz.
It could be a group of power - hungry humans who see the Laguz as a resource to be exploited. They might want to use the Laguz's unique abilities for their own gain, like using their strength in labor or their magical abilities for warfare.
Well, perhaps Naruto finds himself in a world where the Laguz are being oppressed. He decides to fight for them because he sees their struggle as similar to that of his own village. He could use his ninja skills to protect them from any threats, be it other powerful groups or some sort of dark force that wants to take advantage of the Laguz.
It could be a new group of rogue ninjas who have a vendetta against Konoha. They might be led by a powerful and cunning ninja who has a personal grudge against Naruto or the village in general.
It could be a group of rogue ninja who are after the Uzumaki's powerful sealing jutsu. They see it as a way to gain unlimited power and rule the ninja world, so they target the Uzumaki clan, which makes Naruto their main enemy as he stands in their way.
It's hard to say without more details about the fanfiction. But it could be some characters who benefit from Teddy not having rights, like power - hungry individuals or those with prejudiced views.
Well, the main antagonists could be a group of rogue ninja who are hired by a powerful nation to take down Naruto. Since he is unkillable, they would have to use more underhanded tactics like trying to isolate him from his friends and allies. Or perhaps there is a dark force that is awakened by Naruto's unkillable state, thinking that he is a threat to the balance of the ninja world. This dark force could then become the main antagonist, trying to destroy Naruto at all costs.
Another possibility is that an overzealous member of the Order who has gone too far in their methods of fighting Voldemort. Their extreme actions might make Harry think they have become as bad as the Death Eaters, so he starts to oppose them. For example, if this member starts using unethical spells on innocent people in the name of the greater good.
The main antagonists could be the Sith Lords who are secretly pulling the strings during the Clone Wars. Even though Luke is from a later time, the Sith's influence on the Separatist movement is still a major threat. Darth Sidious, in particular, would be a huge obstacle for Luke. He has his own plans for the galaxy, and Luke's presence could disrupt them. So, Sidious would likely send his minions after Luke and try to eliminate him.
There could be a group of rogue witches and wizards who are against the current system in the wizarding world. They oppose the Ministry of Magic's rules and see Harry Potter as a symbol of the establishment they want to overthrow, so they become the antagonists.
Maybe there are powerful dark sorcerers. These sorcerers could be trying to capture Naruto for their own evil purposes, like using his power to open a portal to a dark dimension or something, and Kurama has to protect him from them.
Another type of antagonist could be a strict professor who doesn't like Naruto's carefree attitude and Hinata's association with him. The professor might try to give them a hard time, like assigning them extra difficult projects or being overly critical in class, which becomes an obstacle in their college life and relationship.