You guys wanna know my big bust against the box theory? It's simple: I believe it's fake because it's not hype in the slightest. Yes, you read that right: my reasoning for why it's fake is because it's not cool and nobody wants the reveals to end that way. I KNOW it sounds dumb, but here me out:
1. Sakurai has been giving us everything we ever wanted, everything we ever thought about wanting and everything we didn't know we wanted. Why in the hell would he stop the long-requested reveals at just three unique characters and three echoes when it's clearly simple enough to make more echoes and the list of 11-plus-year-long has barely been half-way completed (Ridley, K.Rool, Daisy and Simon [which I didn't know was so requested back in the Brawl days until just recently] are here, but Geno, Issac, Banjo-Kazooie, Bandana Dee [which I'm upset I didn't know he had such a following as Kirby is one of my favorite franchises that I started playing with Kirby Super Star and the Megaton Punch was my favorite mini-game. I guess I just didn't know he was more than a regular Waddle Dee and I stopped playing Kirby games after Crystal Shards up until Super Start Ultra] and Rayman are still in the dark.). Let me know if there are more characters that were highly requested at the time, I'm going based off what I remember and what I've learned recently.
2. Sakurai has been hyping the crap out of this game. Let's take a look at all the crazy things he's done to make this game hype: I mean, it's called Ultimate, so even it's damn name is hype; EVERYONE IS HERE, and Sakurai meant it with all the returning cast; turns out he also meant it with newcomers and echoes; APPARENTLY HE MEANT IT FOR STAGES TOO, JEEZ!; LOOK AT ALL THE MODES WE CAN PLAY!; Hazard Toggle? Final Smash Meter? the surprise Stage Morph?; Sakurai is catering more to the competitive scene with many of his changes and the options available, yet he's also given casual so much as well; Sakurai has been leaving the big bombs at the end of each Smash Direct (Ridley, then K.Rool); he is also announcing all the characters before the game drops, likely to stay ahead of these dirty leakers
; we also clearly have some sort or story mode coming that is big enough for him to likely dedicate the majority of a Smash Direct to...and there are likely other hype and ridiculous things I've missed. Now I know we all know all these things, but reflect on all that and then imagine Sakurai dropping Story Mode and Ken Masters and Incineroar plus five more stages...and that's it. As much as we have been given (and are hopefully grateful for), it would still be a bit of a Debby Downer if that was how the last Smash reveal went before the game launched. It frankly is a stark contrast with recent events, and thus I doubt Sakurai would let that be the end.
Add in that we still have all of October and November for Smash reveals AND that Sakurai isn't dumb enough to have a digital mock-up box spoil his greatest game of all time, and I think we can be safe that we have much more than just two characters and five stages on the way.