Well, Diddy's basically a given. Really when Rare was at the helm, Diddy usurped DK's title as protagonist, and he's actually just as popular now as DK himself, if not moreso. He's one of those, "should have been in Melee" characters along with Dedede, Pit and Metaknight.
FoulQ was probably just trying to euphamize the phrase "well DUH!" and let you go ahead and do your thing.
Probably the best thing to do is debate whether or not there's any real backing behind the frequency of character occurence on the poll. Like, I think Sakurai already had a vague idea of several characters he wanted and might have posted up those that matched his ideas, or even those that swayed his opinion. With all the millions of letters he probably got, it wouldn't be too difficult to pick an allotment of letters that, individually, were interesting, but as a whole were expressive of Sakurai's intentions.