Though Pokemon games usually come in pairs, it might still surprise you to hear "Pokemon Pink" was supposedly considered as a companion game for 1998's Pokemon Yellow. A reported leak of Gen 1 development material references this mystery game, which might've had Clefairy or Jigglypuff as its mascot Pokemon.
The code appeared on /vp, 4chan's Pokemon board. Dr. Lava, Twitter's "lost Pokemon Lore" specialist, says the code is "almost certainly legit." (Read our profile of Rachel Briggs, the artist who draws the Pokemon Dr. Lava digs up!) That said, this information is far from official, and chan boards are always a shaky source. Absorb it accordingly.
The code, which you can see for yourself on ResetEra, refers to a "pink package" as well as a "yellow package."
ResetEra also points out Pokemon Yellow also "has comprehensive set of audio files of the Pokemon from the Japanese anime in the sound folder," which means Game Freak might've had plans for Pokemon Yellow and/or Pink to use digitized Pokemon voice clips for all the critters, not just Pikachu. The ResetEra post contains a link to a .wav of Diglett's new cry. Be warned: It sounds horrible. It stands as a good example as to why Pokemon Yellow stuck with digitizing Pikachu's voice exclusively.
We all know that the "Yellow" in Pokemon Yellow refers to Ash's sun-colored Pikachu, but where does the "Pink" in Pokemon Pink come from? There's more than one pink Pokemon, but the best answer is Clefairy. Clefairy is Red's first Pokemon in the first (and still going!) Pokemon manga, Pokemon Pocket Monsters. Twitter user SnorlaxMonster also points out the Game Boy Camera has a Japan-exclusive frame that pairs Pikachu and Clefairy. There's a chance the frame might've been made when Pokemon Pink was still being planned—if it was ever planned at all.
Whatever existed of Pokemon Pink is dead and gone, but Pokemon Sword and Shield is alive and well. We even have guides for the upcoming Isle of Armor DLC, so don't miss out.