I Have no clue. I actually wanted this to be a thread were you guys post Plotholes you find, then explain how you deal with them. I used DBZ as an example, then suddenly, it became the thread's topic!
As per age, I'm guessing Raditz is a bit older, since he's seen still younge during Bardock, the father of goku. He could have been a tennager there too though, only a couple years older, so when he came to earth, he was probably like, idk forty-five or something like that, and goku was like, thirty? IDK, alot of guesswork needs to be done to fit it all in agewise. If goku goes by earth years, and radits goes by the longer vegeta years, who knows? They could be the same age!
This is why I like anime's like FMA: Brotherhood, were they explain (Almost) Everything. I like DBZ, do not get me wrong. But sometimes, a plot that doesn't transend the entire universe is better off...