Who could be the main antagonist in an 'elijah x baby fanfic'?

It could be Orochimaru. He's always been interested in unique powers and abilities. The idea of X - 23's mutant abilities and Naruto's jinchuriki powers would be very appealing to him. He might try to capture them both to use in his experiments to gain ultimate power.

A new, mysterious organization that wants to control the chakra of strong ninja could be the main antagonist. They see Inojin and Himawari as prime targets due to their unique abilities. The organization would try to capture them, which would force Inojin and Himawari to fight together and also test their relationship as they face this powerful threat.

An old rival of Dino's from his past could show up. This person might have a grudge against Dino and decides to target Hibari as a way to get to Dino. Since Hibari is so proud and strong - willed, he doesn't take kindly to being used as a pawn, and together with Dino, they have to face this old enemy. This antagonist could have some powerful fighting abilities or some dark secrets that make it difficult for Dino and Hibari to defeat him.

Dr. Eggman could be a great antagonist. He might be creating a new weapon or device that could disrupt the balance between time (which is relevant to Silver) and space (relevant to Shadow). His actions force Silver and Shadow to work together to stop him.

An ancient evil entity that has awakened and sees Ulbert and Demiurge as a threat to its domination. This entity could have powers that are difficult for them to counter, and it uses psychological warfare as well as physical attacks. For instance, it might try to corrupt Demiurge's loyalty or make Ulbert doubt his own abilities.

Vilgax could be a great main antagonist. He has a long - standing feud with Ben and his appearance would immediately up the stakes. He could also manipulate Kevin into turning against Ben for a while.

It could be a character who wants to disrupt Newton's laws in the world where Sackboy has landed. Maybe a mad scientist type who believes that chaos is better than the order imposed by Newton's principles. This antagonist could create all sorts of dangerous situations for Sackboy by messing with the normal gravitational and physical forces.

Dr. Wily would be a classic choice. He has the intelligence and the motive to brainwash Mega Man. He could use Mega Man's power to take over the world or defeat his other enemies.

It could be Beerus. Since he is a powerful God of Destruction, he would see the union of Frieza and Cell as a threat to the balance of the universe and try to stop them.

It could be a powerful superhero who is determined to stop Boxman and Venomous. Maybe a hero from another dimension who has heard of their evil deeds and comes to put an end to their plans.