Who could be the main antagonist in 'Goku Survived the Cell Games Fanfiction' if not Cell?

One possible scenario could be that Goku discovers a new power within himself during the Cell Games that allows him to not only survive but also defeat Cell more easily. Maybe it's a hidden form that he unlocks at the last moment.

Perhaps a rogue Saiyan from another part of the universe. This Saiyan has heard about the Super Saiyan powers on Earth and wants to prove his superiority. He shows up at the Cell Games and challenges Goku and Gohan. He has a different fighting style, more brutal and less honorable than the Saiyans on Earth. His presence adds a new layer of conflict as Goku and Gohan have to decide whether to fight him on his terms or uphold their own values.

Well, Goku is surely one of the main characters as it's related to the Cell Games. He is the central figure in the fight against Cell.

One possible fanfic could be about Goku's intense training before the Cell Games. He might be shown pushing his limits in the Hyperbolic Time Chamber, trying out new techniques and forms to defeat Cell. Maybe he discovers a new power level that no one, including himself, expected.

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.

The main antagonist could be Orochimaru. He's always been interested in unique powers and the cell within Naruto would be something he'd want to study and use for his own immortality experiments.

A rogue military general could be a great antagonist. He has access to military resources and is using them for his own gain, like selling weapons to terrorist groups. He would be a tough opponent for the combined forces of Splinter Cell and Ghost Recon as he knows military strategies and has a lot of firepower.

One possible interesting plot could be Gohan unlocking a new, unexpected power level during the Cell Games. For example, instead of just going Super Saiyan 2, he could access a form that combines the power of both Goku and his own latent abilities. This new form could have unique characteristics like different colored ki blasts or enhanced speed and strength that not only surprises Cell but also gives Gohan a whole new perspective on his power.

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.

Frieza could be a great antagonist. He might see Cell's power as a threat and try to eliminate him while the OC is caught in the middle. Frieza could also try to use the OC to his advantage against Cell, creating a complex web of power struggles.