The recent conversation and the confidence gained from the SourceGaming observations leads me to touch on an uncomfortable subject: What if K. Rool is not DLC?
I think it is important for everyone to seriously consider this outcome and contemplate their reaction.
Firstly, as others have noted, character support groups are coalitions of people. That is, support groups are formed when individuals with varied backgrounds and interests unite to support a character they share in common. Inevitably, this means that despite a shared interest in K. Rool, individual tastes will differ. While some may be tried of "anime" characters, others might want more. To sustain this coalition and to respect other K. Rool fans, I think it is important to keep these differences in mind when we share negative comments about other characters, other series, or the game itself. This does not mean you should not be able to express dissatisfaction with any aspect of the game -- our individual differences deserve respect, too. Instead, this just means you should be thoughtful about what you say and how you say it. In addition to expressing your opinion, your goals should also include minimizing harm.
Secondly, appearances can be used strategically. We are one of the most visited threads in the Smash Bros community -- we are more-or-less K. Rool's "headquarters". Whatever happens with the DLC, we will receive visitors curious about our reaction. If K. Rool is not included, many will visit or lurk this topic just to see the "meltdowns". We should not give them the show they want to see. If you plan on throwing a tantrum or consider it appropriate to do so, reconsider. Not only does it make the rest of us feel uncomfortable, but it also alienates potentially sympathetic ears. While it is justifiable to be upset or even angry if K. Rool is not included, think carefully about how you express this discontent -- vitriol or melodramatic passive aggressiveness does not persuade anyone to our cause. Remember that many sympathetic ears are not as invested in K. Rool's appearance as we are; overzealous negativity can be a easy reason to dismiss our complaints.
My suggestion is to let an emotional post simmer, even overnight. Re-read your thoughts the next day and evaluate the content and style of your message. Consider the following questions: Are you respectfully explaining the reasons that K. Rool's exclusion was a poor decision? Are you remarks unreasonably uncharitable toward Sakurai and the development team? Is your language unnecessarily inflammatory? Effective communication requires people to actually listen to you. People are less likely to listen to you if your substantive thoughts and their presentation suggest you are mostly interested in hearing yourself monologue. Framing your emotions as a "disappointment" can be a particularly effective way of moderating your tone.
Finally, consider that even if you are respectful, there will be people that will refuse to return the favor. If K. Rool is not added as DLC, expect to see condescension and rudeness from random jerks in this forum and elsewhere. This does not mean it is pointless to be civil -- random jerks aren't our only audience. Consequently, even if vitriol is only directed at those spouting it themselves, vitriol in itself "muddles" our image. When two people are flinging mud at each other, many won't care to discern who "started" the exchange. The best we can do, then, is to keep ourselves as "clean" as possible. This is not a "turn the other cheek" philosophy, however. We can and probably should use this to skewer those who try to bully us. Remaining as "clean" as possible allows us to do so by calling out other people's unreasonable behavior. This would not go unused: as many of you know, support groups are not the only ones with the possibility to breed extreme reactions. There is a significant portion of the community that will react with hostility if the game is criticized at all. Taking the "high ground" is probably the most effective tool against these people, as many of these individuals seem convinced that they own this realm simply because they only have positive things to say about the game.
To summarize, be as thoughtful as you can about the things you say in this thread. Imagine K. Rool's exclusion now so that you are prepared if it actually happens later. I have tried my best to do so, too. Note that I still think K. Rool is a likely inclusion. But it is important to think about all possibilities and prepare oneself accordingly.