Talk:List of Unnamed Stands/@comment-80.189.143.57-20150627192452

I think the regeneration that the Nijimura brothers' father can employ is more (if not entirely) due to the fact that Dio's cells, for whatever reason, merged with his own upon death. And, as we know, Dio had the ability to regenerate due to his vampirism; he could only die if his brain was completely destroyed by sunlight or the Hamon, and even in Part 3 after Jotaro's Star Platinum destroyed his upper body, his lower body was still showing signs of life until Jotaro and Joseph took it outside at sunrise.

Additionally, Keicho mentions when recounting his backstory and how his father's mutation came about that Dio had been travelling around the world looking for powerful Stand users - Keicho didn't know what kind of Stand he was looking for, but that his father "seemed to have the potential". And we don't know whether or not it was the type of Stand to have fighting potential, because Pucci's Whitesnake and Johngalli A's Manhattan Transfer would've been good assassins too - Araki just hadn't thought them up at the time, and other than that, there's Over Heaven's non-canon explanation of Johngalli A having been assigned the duty of bodyguarding Pucci (to protect him from getting killed before he could create 'Heaven', I guess).