There could be a dark sorcerer as the main antagonist. This sorcerer is after a magical artifact that Chichi has unknowingly in her possession. And he also wants to use Bulma's scientific knowledge to unlock the full power of the artifact. So he constantly creates obstacles for Bulma and Chichi as they try to keep the artifact safe.
Perhaps a new, self - made android. This android is jealous of Bulma's intelligence and wants to prove itself superior. It targets Chichi to draw Bulma out and try to defeat them both. The android's cold and calculating nature makes it a formidable foe for Bulma and Chichi.
It could be Frieza. He might be interested in Bulma's technology for his own evil purposes and sees Chichi as a threat because of her connection to the powerful Z - Fighters. So he tries to stop their partnership and steal Bulma's inventions.
One possible plot could be that Bulma and Chichi team up for a scientific - martial arts tournament. Bulma uses her intelligence to create unique gadgets for Chichi to use in the combat part of the tournament. This brings them closer as they train together and face various opponents.
Frieza could be a great antagonist. He has a history with Broly and would be interested in Bulma's technology. He might see Broly's new alliance with Bulma as a threat and try to break it up. Frieza could also want to use Bulma to create powerful weapons or devices for his own evil purposes.
There's a possibility that an evil wizard or scientist who has been studying the Saiyans creates a new form of threat specifically targeting Chichi. This antagonist could be trying to use Chichi's new Saiyan powers for his own evil purposes, like using her to open a portal to a dangerous dimension or to extract the power from her to create a super - weapon.
It could be an evil scientist who created the Chichi clones for some malicious purpose. Maybe they want to use the clones to control Goku or to disrupt his life so he can't protect the Earth.
There's a possibility that an evil scientist from another planet could be the main antagonist. This scientist wants to use Bulma's knowledge and Cell's power for his own evil experiments. So he tries to break up their partnership and capture them both for his own purposes. He sends his minions after them and creates various obstacles for Cell and Bulma to overcome.
In this fanfiction, Chichi and Bulma are the central figures. Their different personalities, Chichi's more down - to - earth and Bulma's more adventurous and scientific, clash and complement each other at the same time, which drives the story forward.
Perhaps Mister Sinister. He has always been interested in mutants like Wolverine and could see Deadpool as a useful pawn or a nuisance in his grand schemes. He might try to manipulate the situation to his advantage, causing Deadpool and Wolverine to join forces against him.
It could be a powerful, corrupted Pokemon trainer who wants to capture Cosmog and use its unique powers for his own evil purposes. He might see Cosmog as a key to unlocking ultimate power and doesn't care about the harm it could cause to Cosmog or the Pokemon world. He could also be in league with some dark - type Pokemon that can create obstacles for Marshadow and Cosmog.
Mr. Burns could potentially be the antagonist. He might see the combination of Spongebob and Homer as a threat to his power in Springfield. He could try to separate them and cause trouble for them. Maybe he wants to take over Bikini Bottom as well, seeing it as a new source of resources or power. He starts by spreading rumors about Spongebob and Homer in both their hometowns to turn the locals against them.
It could be Darth Sidious. Since he is always looking for power and control in the Star Wars universe, he might see Naruto as a threat to his plans when Naruto arrives in Padme's world. He would try to eliminate Naruto and use Padme as a pawn in his political games.