https://youtu.be/6b3QRObLD54
So it sounds like that mural leak may not have had every character on it. Spawnwave a supposedly credible leaker said there's more characters and that there's still one "big" character left that isn't on the Mural leak. If it is characters as in plural, maybe Black Knight might be in the base roster? At this point I'm banking on dlc, but anythings possible.
So one theory I saw says that this banner isn't the final version of the banner. Maybe it's for a promotional event that will take place before some final reveals.
As far as BK is concerned: I don't know. All ten of the new fighters are here for really good reasons. They were characters that fans have wanted for years (Ridley, Geno, K Rool, Isaac), or 3rd party characters that have huge significance with Nintendo (Simon, Banjo), or characters that were planned in past games (Mach Rider, Chorus Kids, Chrom) etc. I feel like Black Knight doesn't have any of these things. He would be low-priority given the fact that they are focusing on popular characters. And that's why it's kinda weird to me that Waddle Dee isn't in there. He polled well in Japan; honestly I thought that was all it took.
These youtubers who insist that they have insider info... Some of them leave a bad taste in my mouth. Like they'll go on a podcast and just, unapologetically, in front of hundreds of live viewers... say something like "oh wait, are we not allowed to talk about THAT character yet??" in some cases it's just obnoxious and doesn't add anything to the discussion. You're either wrong, in which case you just seem kind of pathetic. Or you're right, and you're just making the speculation less fun. It's especially annoying that some of them will look at this extremely compelling leak and still say "but... but MY sources said ___ was in so this must be wrong!". Believing their "insider sources" over what's sitting right in front of them. Spawnwave, at least, has retracted his assertion that this leak *must* be fake because his sources have conflicting info. PapaGenos, at least, recognized the possibility that these people were given false info. I think that's probably what happened, honestly. Sorry about the rant, these youtubers aren't super relevant to BK anyway. If Spawnwave comes out and says BK is in the game, I'll be more inclined to believe him. lol