>>18168066>And this is how it began.It is a children game because violence fascinates everyone - children too - and strenght and battles are the very base of a lot of videogames. But we can't feed children some potentially deadly gladiator fights between human beings, since this would "deviate their pure souls", and we can't show humans suffering from hits and gunshots; but, if we make monsters (Pokémon, Digimon), robots (Medarot, Transformers) or shit like this fight instead, it is alright. We give children the violence they need, reassuring the parents through the non-humanity of the fighters.
This is probably the main reason why western producers saw in Pokémon and franchises like this a good money printer. And I don't think the Japanese idea falls too distant from this.
About the in-game reason, I think
>>18168447 is right. They can't explain why, it is just a postulate to avoid a dreadful doubt in children.
This is also why Black and White had, in my opinion, a deep and courageous plot, which is unsurpassed by any other main game in the series.