Pokemon is weird and so, even the simplist things in the games must also be complicated. The pokeball is how you capture and transport pokemon. However, it cannot simply store a pokemons mass as it would cause serious problems outside of weight. For example, the pokeball seems to be about 9.52 cm in diamter giving it a volume (3/4(3.14)(4.76^3)) of 452.11 cm^3 so that the most massive pokemon, Groudon with a mass of 950kg would result in a mass density of 2101 kg/m^3 which is denser than the sun. That's a problem if I've ever heard of one. So this is how I came to Quantum Entanglement, after reading an article that gave a very simple explanation to it on reddit. So when two particles interact in the exact perfect way, they become entangled. This means that whatever happens to one happens to the other, and weirdest part is that the distance between the two particles doesn't matter. Research has been able to do this with particles as large as a grain of sand at a distance of up to 10 miles apart. So, pokeball's are then just quantum computers which turn a pokemon into data somewhere in the universe on how to reconstruct a pokemon. The worst part of this comes with the no-cloning theorem, so that in order for the copy to be made, the original must be destroyed. So every time a pokemon enters a pokeball, the original would be destroyed. If the pokemon breaks free, it is not the original that was encountered, and were it to be caught,  when it came time to battle, it wouldn't be the same as when it were caught. This makes the whole pokemon world a lot more grusome.