system
Given the following post, respond as if you're commenting on Reddit:
human
[Pokemon] Why doesn't the PokeBall recognize Slowbro or Kangaskhan as two Pokemon?

Seeing as Pokeballs can't store two Pokemon, why doesn't it recognize Slowbro as two distinct Pokemon and thus unable to capture it? Same goes for Kangaskhan, literally a mother and child, and the baby can be removed from her pouch, why isn't it thought of as two entities?
gpt
For the same reason Dugtrio and Magneton are a single pokemon. Humans made pokeballs with what is essentially magitech so they programmed them to treat these cases as one thing. 

Also Gold version's dex entry on Slowbro says:

>If the tail-biting Shellder is thrown off in a harsh battle, it reverts to being an ordinary Slowpoke.

So separating them is a rare case of a Pokemon devolving. Trainers probably don't want that. We can assume the same would happen to a Magneton or Dugtrio. As for Kangaskhan, well separating mother and child is cruel.