>>49466863the shrinking concept was only mentioned in manga which not many people actually care
https://tcrf.net/Prerelease:Pok%C3%A9mon_Red_and_BlueMonster Capsule section
>A small Rhydon seen emerging out of a precursor to the Poké Ball, with its button being fond on its bottom rather than on its side, and its red and white parts being swapped. This later aspect is interesting, as it reveals that Voltorb was initially conceived as an upside-down Ball. This sketch also showcases the idea of Pokémon shrinking down to fit inside their Ball, a concept which would only ever find its way in the Pocket Monsters Special manga. 