What if Perfect Cell sought the Dragon Balls and wished for?
Then the Z Warriors would be unable to kill him and he'd win by attrition. So long as he didn't do something stupid such as conjuring a portal to another dimension when he was being beaten by SSJ2 Gohan, he'd be fine. Gohan would eventually tire out, allowing Cell to kill him. If Cell was able to get a Zenkai Boost from healing from injuries due to his immortality, he'd soon be too powerful for Gohan.