Me on the box theory:
65% I believe it's true to an extent... more characters will be DLCs or some very special guest characters are represented on the back of the box, so it's not necessarily stricty 2.
35% I believe it's not true
Me on the blog theory:
99% it's true. But it's also pointless. We will get a number of newcomers that ranges between 2 and 8, you don't even need a theory to reach that conclusion.
The blog theory is so vague that wathever happens it will be most likely true, but by being so vague it also doesn't state any solid information.
What we know is that the remaining characters are less than the already announced ones (9), and anything above 8 would break this rule... so yeah, you don't even need the blog.
1% it's not true and Sakurai will come out with some absurd stuff, either just 1 character or more than 9.
Me on the music theory:
100% it's not true. It has already been proved wrong with the release of 2 Fire Emblem tracks.
Me on Vergeben:
40% it's true... especially if the Square character and eventually Steve are DLCs. It may not be complete and maybe there is someone more that he doesn't know about.
60% there are some valid informations or just a huge amount of lucky guesses, but at the end something unexpected will happen and none of the remaining predictions of Vergeben will be real. The Ken screenshot is very credible but it's just an amazing photoshop work instead. Or maybe Ken is the only correct guess of the bunch.
Me on Famitsu's 108 stages thing:
95% it's real, there are 5 stages we know nothing about and that will be announced soon.
5% it's just a typo.
Me on Donkey Kong's Karate Joe hint:
65% it's just a coincidence, they took inspiration from the same cliche.
35% Karate Joe is in the base game! It's not only that hint, it's because many people requested for a Rhythm Heaven character and Karate Joe is the one Sakurai figured out a moveset for.
Also there is a very detailed Karate Joe leak that's been overlooked since after Isabelle's Direct, but it's technically not completely debunked yet (they may have switched the reveals last minute to dismiss the leak). I'm not refering to the gameplay screenshots, that was fake, I'm talking about the memories post.
Me on the Ballot/Popularity theory:
99% false. Sure Sakurai selected some picks also on popularity and ballot results, but he won't let fan requests get over his creative freedom that much.
Especially, those poplar choices are either echoes, or characters who are historically or relevancy-wise very important to their respective franchise, and they're not only selected by popularity, popularity only helped.
Add that the Ballot was not only about the amount of votes but also about the motivation written with the submission of the vote.
1% it's true... well, actually, Sakurai may be against that, but he's forced by Nintendo or something... kinda like he tried to avoid Masked Dedede as final smash for 2 games in a row but now he had no choice but to include it.
Me on the chair theory:
100% it's true, it's the proof that Susie from Kirby Planet Robobot is going to be in Smash, think about it, they're clearly ergonomic seatings, It can't be wrong!