A recent leak of unused Pokemon Diamond and Pearl sprites offers a cool new fact about the 2006 Nintendo DS RPG: Most of the Pokemon in the game, if not all of them, were initially supposed to have distinct male and female variants.
Lots of Pokemon demonstrate sexual dimorphism—female Pikachu have a little heart shape at the end of their tails, for one—but the examples collected from 4chan's /vp/ by cut content expert Dr. Lava go above and beyond. Gen 4's unused female Pikachu sprite doesn't just have a heart at the end of her tail; she's also lop-eared. Female Raichu is lop-eared as well.
Other noteworthy examples of gender differences that were scrapped include a female Charizard bearing a single horn, a female Arcanine with a swept-back mane, and a female Mudkip with a shorter head fin. Female Plusle have smaller ears, and female Marill have a larger ball at the end of their tails.
The Gen 4 Beta Sprite Leak:The new Pokemon leak just revealed tons of gender differences that ended up getting scrapped from Gen 4's release versions. I've just published a lengthy article explaining the what, where, when & why.Link to the full story: https://t.co/2z188faFPx pic.twitter.com/2GT3EwMJ0P— Dr. Lava's Lost Pokemon (@DrLavaYT) December 20, 2019
It's a cool historical info dump, but is it legit? Dr. Lava points out that crafting so many alternate female sprites would be an awfully elaborate hoax. Granted, people have gone further to pull a fast one on fans; every new Pokemon generation brings legit looking "scans" of "official" documents that leak the starter Pokemon's final evolutions. A more concrete bit of proof that these sprites are the real deal can be found in the Summer 2006 edition of CoroCoro Comics, which mentions Diamond and Pearl's Pokemon will show substantial physical differences between males and females (translation via Bulbapedia).
The final release of Diamond and Pearl didn't keep all those differences between its male and female Pokemon, and sexual dimorphism has been used selectively in subsequent games. Why was it scrapped? Dr. Lava lists some probable reasons. For starters, rendering all those alternative sprites would suck up a ton of development resources for little financial gain—though I imagine fans would love to see the effort. For another thing, it'd be hell to keep tally of the differences for the anime. "And since it was mostly the female designs getting changed, in retrospect it might look like every Pokemon from older games and anime episodes were male," Dr. Lava adds.
It's not that unusual for leaks of beta Pokemon to find their way into the wild. Last year, we were treated to never-before-seen Pokemon from Pokemon Gold and Silver's Space World 1997 demo. The Pokemon Diamond and Pearl gender differences aren't as dramatic—in fact, all the available examples involve older Pokemon and none of Gen 4's newcomers—but lost Pokemon history of any kind of a joy to delve into.