I brushed up my old Zygarde Core aka Squishy sprite from the previous project circa late 2015.
As Showdown won't be needing BW-style Zygarde Core sprites, these are targeted more to fan game makers and anyone else watching this thread.
leparagon Many of aXl's sprite drafts from the early stages of the XY Sprite Project used the technique you describe above, and Layell and I generally removed it in QC. While I can't speak for Layell's reasons for doing so, for me, it was because this style of anti-aliasing tends to show up poorly on dark backgrounds. This is relevant because many of Showdown's battle backgrounds are medium rather than pale in brightness, so for this project, it's important to keep in mind how each sprite will look on non-white backgrounds. I myself am guilty of always spriting on pure white canvases, which is why I like to test what I have against random backdrops (something like
this). Smogon's current forum layout having an off-white background doesn't exactly help matters.
Also, correct me if I just missed it, but I noticed that most of the sprites you linked don't use the exact technique you're discussing. An example of a BW sprite that makes extensive use of it is Tropius:
My stance is this kind of "zigzag" anti-aliasing is best when used sparingly and for the internal details of a sprite (such as Zygarde Core's eye above) rather than along the external outline. It's still early in the project to hone in on minor details, and we can always shelve Bewear's front sprite for now and return to it when we have a better idea of what the rest of the new designs will look like for the sake of stylistic consistency.
While we're on the topic of outlines, I'd like to highlight some less optimal ways of colouring outlines and alternatives to them:
Above is the same curve coloured in two different ways. The example on the left is fine (outer black, inner colour), but in the right-hand example (outer colour, inner black), the inside colours and coloured outlines form a "corner" rather than a smooth curve when shown on a darker background.
These are two different approaches to anti-aliasing on outlines. The external anti-aliasing on the left is present on some past gen official sprites and blends in well on light-coloured backdrops but stands out on dark-coloured ones. The internal anti-aliasing on the right is safer on all backgrounds.
Those are just a few spriting-related pet peeves, and hopefully, my MS Paint diagrams aren't too terrible to comprehend. Thankfully, outlines are generally pretty easy to fix via some redrawing and recolouring.