I'm gonna provide three alternative histories to explain the grinch leak. One's that contradict the official story in several ways. The conclusion that i've personally come to will come at the bottom of this sure to be long post. History tell's us one thing, leaks tell's us another, but often times the truth is something in between. So consider this speculation into the true nature of the leak.
Story 1 - The Revenge
In this version. A man who used to work for Marina was contacted by a fellow employee via snapchat. This was a friend of the former employee. This former employee did not leave Marina on happy terms. In fact, he was fired. However he left with good friends who hated the fact that he was fired. Often times these friends would send him photos and videos of what they were working on to keep him in the loop. This was an act of courtesy on the friends part, because Marina get's more hot scoops then ACP, his current job. Marina get's contacted by Nanmco in order to print out material for an upcoming private media event sometime in novemeber that will take place in europe. Obviously they take the bet. Seeing it as the chance of a life time to get revenge, the friend sends out "leaker" a snap chat video of their current works, including smash bros. The fired workers name is in the image because the friend could have had several people he wanted to show this too, and out fired man just so happened to be apart of them. So that explains the poor blank out attempt. When it lands in the hands of the man at ACP, the person who got fired from Marina in this version of the events, he posted "lol" and "**** Nintendo" on it out of spite. Seeing that his name was blacked out and it was safe to ruin the surprise, he ran to 4chan to post the images. Hoping that Nintendo would rain hell upon Marina when the internet inevitably picked it up. However, the internet found that his name was still in the video. And thus traced him. Revealing he had experience with both Marina, and ACP. Marina deny's on the grounds of NDA to damage control, and are currently trying to find the point at which the leak started in privacy. ACP is completely innocent and the man who was fired who posted this is being honest when he says he has no connection to the leak. He didn't produce the video. He just posted it. It's not his fault it leaked. From there, this entire mess began.
This story requires a lot of assumptions. But more or less covers every corporate hole in the leak.
Story 2 - The Mastermind
In this version. The chad dorf bleaker was actually a genius level intellect individual. One who wanted to enact his magnum opus of leaks into the real world at all costs. He knew that a simple text leak wasn't going to cut it. This had to be big. BIG. The biggest hoax in smash history, in fact. One of the biggest hoaxs EVER in gaming history, in fact. He saved every penny he could. He reached out to a professional graphic artist somewhere in the world, pottentially someone at ACP. And he paid them everything to produce renders for the characters within his orignal leak, produce a new battlefield, and then build a storyline that reaches into the stratosphere. covering every single out that a human brain could comprehend. He knew that battlefield had changed. So he actually told them to redesign battlefield for the empty slot. He knew that smash fans would evaluate every detail, so he told them to put in stuff like Isaac being next to fellow AT's. He knew that people would question character placement, so he had Jigglypuff and Mii fighters moved to specific locations. As for the storyline, he privately verified with ACP, and Marina, if he could borrow the likeness of a former employee at Marina, and current employee at ACP for this. Probably waiting weeks just to verify with various levels of management. He then had the video created. Intentionally only half blanking the name, knowing that the internet would naturally hunt down this guy. He was the one who posted the image on discord, and then 4chan. This man has near genius level intellect and wanted to make a point to prove his skills.
This story assumes ever MORE then the first. But it explains the lengths someone would have to go through to fake this and have every tiny detial line up as things have.
Story 3 - The Hoax
In this version. This is a real leak. But the story is entirely wrong. What actually occurred is what is referred to as within the industry as a "controlled leak" this is when developers intentionally leave files to be datamined in their games. When trailers "mysteriously" drop months ahead of time on random youtube channels. When rosters for fighting games drop "suspiciously" on 4chan. The general thought that leaks are a detriment to hype is actually wrong. This can be proven mathematically with Monster Hunter World. It had leaked half a year earlier on 4chan that Monster Hunter PS4 was a thing. This drummed up a LOT of hype, and when the announcement came, it was met with universal acclaim. Controlled leaks are created to sasiate the tastes of the mega fans who are the ones who go out and talk about this stuff to their friends, they're the ones who make youtube videos discussing all of this producing millions of dollars worth in free advertising. That way, when the offical reveal hits, people were already invested. Nintendo has employed this tactic several times, most notably in the case of the Switch's whole reveal cycle. What this version of events proposes is that the leak was created by Nintendo, and spread by their employees on order to generate hype for next weeks smash direct. Why leak Smash? It's the biggest game they have this year, and if they want to sell 20 million consoles this quarter, they will never every single last drop of hype they can get. By extension Incinroar and Ken and box theory were all created by nintendo, so that when the big leak dropped there would be a whip lash of expectations and hype. They spread incinroar around the surface leak community to lower expectations, only to blow them out of the water drastically when the real info hits. This by extension, will translate into money. The name and all that were just stories nintendo created to accompany this.
This story assumes that Nintendo corporate convinced Sakurai to leak, which is a difficult call to make. But it is entirely plausible is Sakurai were made to understand the stakes, Assuming they were able to convince him that most people outside the super die hard community would still be surprised. Thus it was a worthy gamble.
Personally I believe we're looking at a legit leak combined with a controlled leak. Controlled in that Nintendo let Incinroar and Ken slip on purpose to drum up anti hype. And a legit leak occurred spoiling the fruits of the anti hype.