Manny the mammoth from Ice Age has a good chance of survival. He's strong and has a lot of experience dealing with the harsh Ice Age environment. He could protect the more vulnerable Total Drama characters and lead them to safety.
In my opinion, Alejandro from Total Drama would be likely to survive. He's very intelligent and manipulative, which would help him form alliances with the Ice Age animals or other characters. He could also use his charm to get out of difficult situations.
Courtney from Total Drama might also survive. She's highly organized and determined. In the Ice Age world, she could use her leadership skills to keep everyone in line and come up with strategies to find food and shelter. She would be strict about following rules to ensure everyone's survival.
Naruto himself. His determination and never - give - up attitude would serve him well in the challenges. He's used to facing tough opponents and difficult situations in his own world, so the physical and mental challenges on Total Drama Island would be just another hurdle for him to overcome.
Naruto himself would be very likely to survive. His ability to quickly adapt, his large amount of chakra, and his powerful jutsus like the Rasengan would give him an edge. Also, his determination and his will to protect others would keep him going even in the toughest situations. Another one could be Sasuke. With his Sharingan, he can predict his opponents' moves and his skills with a sword and ninjutsu are top - notch.
Another interesting concept is to have the Ice Age characters compete in a Total Drama - style competition. Sid could be the comical underdog, always trying his best but getting into hilarious mishaps. Diego might use his hunting skills to an advantage in the challenges.
Will might also have a chance. He is charming and persuasive, which could help him form alliances. He also has a strategic mind from his work in the law firm, and he could use that to outwit his opponents in the Hunger Games.
Sasuke and Duncan might form an alliance. They both have a bit of an edgy and brooding personality. They could respect each other's skills. Sasuke's ninja skills in combat and Duncan's street - smart and tough - guy attitude would make them a formidable pair in any challenges they face in the crossover.
Harry Potter and Owen. Harry is brave and resourceful, and Owen is friendly and easy - going. Harry could use Owen's positive attitude to keep the team morale high, while Owen would be protected by Harry's magic skills.
Lex Luthor. He's always looking for a way to take down Superman, and an apocalypse would be the perfect time for him to make his move. He could be using the chaos to build some sort of doomsday device or manipulate events to his advantage.
Rick from The Walking Dead has strong leadership skills. He could organize the wizards and witches and lead them in battles against the undead. In the Harry Potter world, Severus Snape could survive. He's a master of potions and dueling. He could use his potions skills to create antidotes for any possible new diseases brought by the undead, and his dueling skills to fight off both the walking dead and any threats from the magical side.
Ruby. She's extremely fast and has shown great combat skills. Her ability to quickly move in and out of danger would give her an edge against a Xenomorph. Also, she has a strong sense of determination which would help her stay focused during such a terrifying encounter.
Owen is also a fan favorite. His humorous and friendly personality brings a light - hearted touch to the often - tense situations in Total Drama. In the 'X Overs' fanfiction, he can interact with new characters and get into all sorts of wacky adventures that fans love to read about.