>>49372560pretty sure the inside of a standard pokeball is placed with mirrors or various reflected surfaces depending on era, the ball dissolves pkmn into data which looks like a light/laser
thanks to the mirrors the light is constantly bouncing around, and then contained until released
it is literally a means of enslaving these creatures and registering their unique data to a unique pokeball so that they only obey you
there is a bunch of different ancient containment tools from crystal orbs to stone relics
https://bulbapedia.bulbagarden.net/wiki/History_of_Pok%C3%A9_Ballsthe standard pokeball was probably just the product of a long line of research and prototypes, most of which were probably spearheaded by individuals seeking power and weapons for war throughout the ages, until the technology got so widespread and streamlined that a kid can go to a store and buy a ball
the creator of Digimon had a similar idea; the original concept of it was that Digimon are creatures from myths and folklore, gods, deities, etc. given a physical form due to the advancement of technology.
In other words, they existed in a different plane of reality sometimes crossing over which resulted in folktales, technology was able to convert their data into a physical manifestation in this reality.
Their "mon" names are merely a simplification of data code since their real name can't be translated into human language.
If you think this all sounds like ShinMegamiTensei then yes, both Pokemon and Digimon were inspired by such, although Pokemon is more like capturing spirits and sealing them into objects.
The "shrinking" mentioned at the start of this game is probably just a weird choice of words where he is trying to "scientifically" explain that pokemon touched by balls "shrink" down in size and get sealed within it.
or a poor translation
or he's literally talking like a toddler
