Stan could be a likely hero. He's often the voice of reason in the show. He would probably be the one to come up with a practical plan to survive the zombie apocalypse, like finding a secure place to hide and stockpile supplies. He also has a strong moral compass which would help him make decisions about whether to help other survivors or not.
Kenny might be a hero in his own right. Since he has the unique ability to come back to life, he could be used as a sort of guinea pig to test different ways to defeat the zombies. He could sacrifice himself multiple times to gain knowledge about the zombies' weaknesses. And his rough upbringing might give him an edge in the harsh zombie - infested world.
One idea could be that the kids of South Park form their own survival squad. Cartman might try to hoard all the food, leading to comical in - squad conflicts. Another could be that the zombies are actually the result of a failed experiment by Professor Chaos, and the boys have to find a way to reverse it. Maybe Stan and Kyle have different ideas on how to deal with the zombie threat, with Stan being more practical and Kyle more idealistic.
Harry Potter himself would be a likely hero. He has already faced Voldemort and numerous other dark threats, so he has the courage and experience. His ability to think on his feet and his connection to the powerful Patronus charm could be very useful against the zombies.
In South Park, there was a strange occurrence. A new kid moved into town, but this kid was a bit different. He was a super - smart alien in disguise. The boys, being the curious bunch they are, quickly noticed something was off. Cartman thought he could use the alien to take over the world, Kyle wanted to help the alien fit in, Stan was just confused, and Kenny was along for the ride. They all got into crazy adventures as they tried to figure out the alien's true motives and protect South Park from any potential threats.
Obviously, Stan, Kyle, Cartman and Kenny are the most likely. They're always at the center of the action in South Park. Their different personalities would lead to really interesting time - travel scenarios. Stan's more level - headed nature might be the voice of reason during time - travel chaos. Cartman would probably be trying to use time travel to his own greedy advantage, like finding a way to hoard all the cheesepuffs in history.
One idea could be that the heroes have to use their quirks in new and creative ways to fight off the zombies. For example, Bakugo's explosion quirk could be used to blow up large groups of zombies at once. Another idea is that some of the students get bitten and start to turn, creating a moral dilemma for their classmates on whether to save them or put them down. And a third idea could be that the zombie virus is actually a new type of quirk that has gone out of control, so they need to find the source of this 'quirk' to stop the apocalypse.
It could involve crazy chases with zombies in colorful settings. Maybe there'd be heroic characters using funny weapons to fight them off.
Definitely Harry Potter himself. He has faced so many dark and dangerous things already, so he'd be able to handle zombies. Hermione would also be a likely survivor. Her vast knowledge of magic and quick thinking would serve her well. And Neville Longbottom. He has shown great courage and has a deep understanding of Herbology, which could be useful in creating defenses or finding antidotes.
In general, it's not highly popular. The concept of mpreg in South Park fanfiction is a very specific and somewhat strange concept that appeals only to a particular subset of the South Park fan base. Since it goes against the normal biological and story norms of the show, it doesn't gain as much traction as other fanfiction themes that stay closer to the original spirit of South Park.
Well, Kyle could be a strong contender. He's intelligent and has a strong sense of justice. He'd be able to strategize well and form good alliances. However, his temper might get in the way at times. Another possibility is Stan. He's fairly resourceful and has a good heart, which could help him gain allies, but he might be too hesitant to make tough decisions sometimes.
Toga might be interested in the zombies in a different way. Since she has a fascination with blood, she could study the zombies to see how their blood or 'undead' state works. However, other villains might just be in it for themselves. Dabi, for example, might just burn his way through the zombie hordes without much thought for a grand plan. He'd be more focused on his own survival and causing chaos.