So then add Dreamland 3 and Triple Deluxe's keychain. It still doesn't really help that much.
There is a single entity of Dark Matter, it's referred to as "Real Dark Matter" (Which is the one in the chart). It's really no different from having Bandana Waddle Dee or Toad in the chart.
Uniqueness is subject to one's own personal opinion. So iunno if the chart would be marked as valid, especially seeing how biased you are on some of these characters as well.
No, there isn't a single entity called Real Dark Matter. It was in KDL2 maybe, then after the second attack it was demonstered that there are lots of Dark Matters and the leader entity is Zero, who even creates them during the bossfight.
Also that chart is not biased in any way, if it was biased, I would have put Prince Fluff and Magolor a lot lower. If you actually read it, you'll notice that it's based on how many time those characters appeared and how big their role was in each game where they appeared.
I don't want to continue the discussion about the bias as I stated before, I don't want flames all around.
(the only "biased" part is the moveset potential one, because it's obviously based on personal opinions; anyway I excluded those scores from the second chart).
I just did some analysis with some datas.
The importance of the role is based of how the characters contributes to the story of the game, and being an important character in the story is more important than being playable in the chart, as many characters like Zelda are important but they have never been playable, for example.
EDIT: English is not my main language, I'm Italian
Yoshi is a species but it also represents a franchise, Yoshi's Island. I doubt he would have been playable if that franchise wasn't created. For the same reason, I think that Cpt. Toad makes a lot more sense than Bandana Dee, despite both of them being generic creatures made different by a detail. CPT Toad has a spin-off franchise, and an unique gameplay to represent, while Bandana Dee is just Dedede's sidekick. He has many chances of being in, but those chances are only due to his high popularity, because his roles in games weren't really much different from Toad's (a generic one, not the captain). If Sakurai decides to take popularity in consideration, then Bandana Dee would surely be in, but if he uses another method to choice his characters, I doubt he would have many chances (as Toad proved in the past, twice in a row, probably thrice). but that's a whole other argument.
EDIT: I already speculated time ago that this time we will not get any Kirby newcomer. I hope I'm wrong, but by my logic, all other characters outside from Dedede and MK have not chances enough to be in. The only one who would make a bit of sense is, yes, by my logic at least, Adeleine, and I think Sakurai won't put her in the roster because he doesn't want human characters in Kirby. That's my prediction, and it's very bad, how can this be biased?
The only "hope" is if he takes popularity in consideration, then Bandana Dee would be possible (and I don't even want him), he's the only one that could make into the game, but the chances are still low (like 30/40%), at least by my speculation. The chances have been raised a bit with the inclusion of Lucina and Robin, because Lucina/Marth (depending by the point of view) is not that necessary to the roster but he included him/her anyway. This opens the doors for some characters with low chances, but at the same way, with the confirmed and the veterans, the roster is becoming too big, and since the icons of the characters have to be all in one screen (at least on WiiU) to allow more player to select the characters at once, the number of newcomers is still very limited.
Anyway, it's very cool (sarcasm) how each time Adeleine is mentioned in this thread, a war starts.