Alright, here, I'll type up a full explanation of where this roster came from.
The first piece of the roster's origins is perhaps our earliest credible leaker, NyaseNya. Shes a member here who, three days before Sonic's Dojo update, posted on our Sonic thread that she had just learned that his update had been moved from its originally intended date near the release to that Wednesday, though she didn't know why (we of course since learned this is because of the first delay). As we all know, she was proven correct. She went on to give various uninteresting tidbits of info about Brawl's development, including the semi-interesting claim that it would be on a dual-layered disk; then a little over a month later gave a leak regarding characters: she said there would be 35 characters (excluding transformations), confirmed the presence of Olimar, Toon Link ("WW" Link to most of you), Ness, and Mr Game & Watch, said that Olimar would have a pikmin-based whip-like attack, and claimed Mega Man was not in and that Ridley was most likely just a subspace boss. Needless to say, she got a lot of hateful responses to this, and Gimpy edited her post to say she was faking and locked her thread. A week or so later she came back and claimed to have learned that Brawl would be delayed again in the US, again received a lot of flaming, and hasn't been seen since. As you can see, a number of her claims have since come true (Ness, Olimar w/ Pikmin Chain, delay, most likely Mega Man is out based on the Inafune podcast).
Second is another credible leaker, ChaosZero from GameFAQs. On Halloween, he posted that Wolf, Falco, Lucario, Sheik, Captain Falcon, and Ness were in, Final Destination was back, Mewtwo was out, and gave a precise description of the Dragoon item. As we've seen, most of what he has said has since been proven true - Sheik, Lucario, and Ness have recently been revealed, the Dragoon is now well-known, Final Destination has just been either confirmed or heavily hinted at, and although it isn't technically confirmation Serebii has heavily hinted that Mewtwo being cut is true.
Third is a less-known leaker, ShadowXOR. He was a consistent poster over on ChronoBound's character analysis thread, and during the wave of false "prophets" commented that a few were either very lucky or real based on what he knew. Obviously, this prompted other posters to question him, and eventually he said that he had been told that Captain Falcon, Ness, Marth, and R.O.B. were in. He didn't immediately go too public with this, since he didn't want to be flamed like all the other "prophets," but eventually someone must have convinced him to, since he mentioned this in the leak index thread and made single topic about it on GameFAQs. ChronoBound, myself, and probably a few others believe him based on what we've seen of his posts - I at least am absolutely convinced he is not the typical attention-mongering fake leaker we've seen, and if hes wrong its due to misinformation, not lying. In any event, one of his claims, Ness, has since been proven true.
Using the above three, ChronoBound compiled the 35 character roster for the first time, although he only posted it fairly deep in his own thread and didn't do anything else with other than say "if these three are right, this is our roster ."
Sometime later (I'm not sure when, but shortly before NeoGaf entered the picture I believe), another leaker showed up on GameFAQs, PortraitofRuin, who is known for leaking his namesake game. He claimed to know the full roster and the exact order on the character select screen it would appear in. By now you've all seen this, since a mock-up has been made of it, but it corresponded perfectly with ChronoBound's compilation, and seems to fit with the recently-leaked images of the starting roster as well. He also claimed Ridley, Takamaru, Krystal, and Isaac are not playable. As far as is known, he is not active on these boards, and so it is highly unlikely at best that he saw the one or two posts ChronoBound made with that compiled roster before he showed up.
Most recently (over the last weekend), we have NeoGaf enter the picture, and it is because of these guys that the roster became as prolific as it is now. MarkMan posted on one of their threads in a way that implied he had inside knowledge of the game, and when questioned was willing to admit that he knew there would be 35 characters, 41 stages, and that Sonic was "a b*tch to unlock" (his exact words). Another poster, Reno, claimed this fit with information he had as well. MarkMan went on to say that there were no unknown third-party characters, Ridley was out, Falco and Wolf were playable (and not alternate costumes), and "Wind Waker" Link was in. Reno affirmed these claims, and shortly thereafter posted a complete list of newcomers, which was essentially those they'd already mentioned plus the Dojo's, Lucario, and R.O.B. He went on to affirm Marth's presence by correcting someone's final roster compiled based on their claims, essentially confirming the same 35 character roster ChronoBound had compiled and PortraitofRuin had leaked. These two are both well-known leakers on NeoGaf who have given information about a number of games (apparently in Reno's case mostly fighting ones), and if they are wrong they will be IP-banned there, as is that forum's policy, so they stand to take a major loss (both of their credible reputation and their accounts on that forum) if they're wrong.
Interestingly, one of NeoGaf's mods, sp0rsk, stood up for them, saying "Reno is not lying." Now, most of NeoGaf's mods are members of the gaming industry, so its likely at least one of them does know whether this is true or not, which makes this significant (plus if they IP ban members spreading misinformation about upcoming games, you've got to imagine they have similar policy for mods, so this isn't something sp0rsk would do lightly).
Also interestingly, once the NeoGaf leak got out, Serebii stated that he could not deconfirm it, although he had done so for many other leaks. He did add that he thought it seemed to small, but that since he does not know the full roster, he cannot be sure if it is real. Oh, and though he did not say it outright, his post upon learning of the Lucario leak very heavily implied that the implication of Mewtwo's removal people had drawn from his past posts was true.
And thats most of what I know about this. Theres a few more tidbits associated with a couple of the leakers, mostly Nya, but little of it relevant and none of it confirmed (some of it will probably never be known if its true or not). As you can guess, I've been following this for a while, and all I've seen of it has me pretty well convinced this is the real deal. Theres just too much overlap among the leakers and too much evidence that they're credible for me to believe otherwise, not matter that I wish it weren't so.
Zevox
Diese Woche können wir endlich mit sogut wie allen Infos rechnen 
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