KANTO'S WAR

This is an old legend that says that there was a war in Kanto. Games argument have a bit to do with this subject. You're a 10 years old kid. The world is plenty of old people and kids. Adults are a kind of mafia mans (Team Rocket) or Gym Leaders.
 There are hospitals everywhere and also gyms, there are no roads, no freeways, even vehicles. At games, you have no father, your rival too. This can be they died at war. Lt. Surge says that Electric Pokémon saved him at war and he is maybe one of the only adults at game.
So this may be true, we role play the first generation after a war. Pokémon 1st Generation was  the darkest one so this is obvious all these stuff can be true.