I don't have all the time in the world right now, so Koopa, I'll get back to you later on.
@Toise
For the most part yes, that is a fairly good correlation. While the middle tier of Nintendo series seem to have discrepencies in regards to their exact amount relative to each other, they are still cleraly in a middle tier of characters as opposed to the lower tier Nintendo series which generally don't have much of anything. Plus, I'd chalk the DK series as something that was intended to fit in there. If it wasn't for technical difficulties, it would have Dixie in there, and would have had three characters (still two slots though) and that would balance out things fine. Heck, the other series work there well too once you accept the fact that certain series like F-Zero and Metroid just don't have the characters in general, and Wario/Yoshi series are still pretty tied into Mario. (Though as I admit later on, Wario much less so)
And I actually didn't read you Wario/Dedede thing correctly before. I thought you were reffering to them being unpopular, which didn't make much sense to me. In any case, for Dedede we actually did get an explanation that Sakurai didn't want to seem like he was favoring his own characters back at around Melee, but decided not to worry about that with Brawl since he wasn't part of Nintendo any more. For Wario, I'm not quite sure. At the time he was still part of the Mario series of characters, and its possible he just got cut out because there were already two new Mario characters already in Melee (and Doc was just easier to put in)
As for Goroh and Ridley, we also have a explanation why Ridley wasn't in by Sakurai himself, which had to deal with the mechanics of him. Even so, both he and Goroh are still somewhat obscure, though Ridley less so. Goroh's direct disclusion though could just be another factor of him just not having any traditional skills to work off of at all. Remember Captain Falcon's inclusion in the first place was likely just a because he was given the moveset of those dragon-fighter-whatevers that were in the prototype version of Smash. Whle Goroh has other reasons for being the next F-zero character in line, the only real reason I think he has a significant chance is because they could just BS a Samurai moveset in there. As a character he is very underdeveloped, and if it wasn't for that moveset pottential, I'd say that it would be best to give a second racer style moveset to someone from the Excite-series.
And we first had a debate back in one of those DK ones? Its been so long since then. I still hate K.Rool, but I guess at this point there are a bit too many fans complaining for him to be in that I can't ignore that he has significant chances. Still Smash would be better off without the generic putz. :V
Back in the begining of the Wario series there were Goomba-esque things and they are still there in Shake it, but I get your point. I still think though that Wario's still considered a major character in the Mario series itself (Mario 64 for the DS had him as a playable character for instance) though he can equally be seen as a character from a different series. Thus despite the fact that he has his own series, the fact that he still was the next character in line for the Mario series, makes it so he sort of represents both, which as I said to Koopa, is reflected in his overalls look.
And I don't have a real character theory or even a character list. In my head I rank what makes sense for the new character of each series, and then I think of how the series should be represented. The bolded part of the quote is quite obvious in that if everything was determined by sales/popularity, we'd only have about three of four series with everything else getting nothing, but its still clear to me that the more popular series still do get more representation, be it characters, items, or stages, if they are more popular.