I'm going to continue to call shenanigans on this leak until the game is released and I can see the full roster for myself. Even if we do get a PotD or other character reveal that matches one of the newcomers/unconfirmed vets, that doesn't necessarily mean that the entire leak is true.
However, for you believers out there I will say that even if part of the leak is proven false (Dark Pit revealed as a Stage Boss/Duck Hunt revealed as an AT similar to Color TV-Game 15 are my most plausible guesses), that doesn't necessarily mean that ALL the information in this leak is false, although it will officially disprove the leak itself.
For me, although some of the images do seem very well-done (props to whoever made this), there are some inconsistencies that go against the otherwise professional appearance. One example of this is that while the Duck Hunt, Ness, and Dr. Mario renders all look amazing, Wario is missing an entire pupil. No it's not partially hidden behind his nose, it's simply not there at all and you can see this if you zoom in enough. Also, notice how Shulk, Ness, and Dr. Mario all have the same shade of red as their backgrounds, when all the other character have their own color background (even if it's a slight difference in shade). It may not seem like much, but why would they simply slap the same color on 3 different characters (all of whom just happen to be unannounced at this time) when prior to that they took the same to make sure that each of the 37 announced fighters all had their own unique color background?
Although these are, for the most part, minor details, I find it very hard to believe that these things would slip by the design team unnoticed. Just my 2 cents, but at the end of the day I'm calling fake. Thoughts?