Many pieces of content, for one reason or another, do not make it to the final build of a game's end product. This last Thursday, an anonymous user posted a link on 4chan's /vp/ board, containing supposedly leaked Gen 4-era beta sprites. Over 1500 images were included in the uploaded file, with images for both male and female Pokemon.
While the series has included more and more species with sexual dimorphism (female Pikachu have heart-shaped tails, for instance), not all Pokemon exhibit it. According to Pokemon content creator DrLava, much of the sprite work lines up with pre-release materials. 63 out of 386 Pokemon received gender differences, many difficult to notice, in the final product. Most of the content in the leak concerns Pokemon from Gens 1-3, suggesting it was before many of the Gen 4 Pokemon were designed.
Though it's unclear why these sprites never materialized in the final product, DrLava has a theory. Because Gen 4 Pokemon sprites feature a short animation when appearing in battle, animating a second sprite for each Pokemon was simply too much work. Due to the sheer amount of work required and the consistency with in-game data, pre-release materials, and supplementary development information, DrLava concludes it's unlikely that the leak is a hoax.
As for the original leak? Within 24 hours of the leak, the owner of the website was doxxed, presumably by one of /vp/'s users. The sprites were removed and replaced with a message:
There are a number of reasons why I took this page down, and I’d like to address a few things.
First off, people are making the connection between this site to Helix Chamber, and I can definitely see where they’re coming from. Someone from Helix Chamber asked if I could host something on my site a while back since I’m in the dev/proto scene and I own the [redacted] domain, so I agreed. I deal with this kind of thing on occasion, so it wasn’t an odd request.
This site has no affiliation with Helix Chamber, and apparently they’re catching some flack over this, so I wanted to make it known that this was a page I made to pass around to a few people, and that Helix Chamber didn’t have any involvement with this other than reporting on it after release.
Additionally, the sprites were given to me anonymously through Tox some time ago, and while it initially appeared to be a gen 4 sprite dump from the sprites I looked through, I wasn’t entirely sure of their validity, so I saved them and moved on. I’d forgotten I held onto them until I was going through a few old files and stumbled across them. I looked through them all again and noticed one of the Pikachu sprites was lop-eared, and the Weavile and Munchlax sprites matched up with an older design shown in some early screenshots. I decided to make that comparison table I had up here for a few months so I could more easily compare them.
Someone I initially gave it to posted the link on /vp/ recently, and a few users have been going out of their way to find the source. I read over the thread, and while most people expressed interest in or enjoyed the sprite table, I’ll be taking it down to prevent any further harassment and to stop those who are trying to uncover the source, which will result in the exact opposite of what those people want."
Though the original leak is gone, Internet denizens have already copied and uploaded the sprites elsewhere.