First off all, what are pokemons doins when they enter a pokeball? If we base pokeballs on the quantum transfer, we can say pokeballs are doors to different dimensions, enabling pokemons to beam into another physical space! Keep this in mind.
To look after all those kids at the age of 10? Because, all the fuel and energy sources has run out and that led to a war, which killed all the soldiers and nearly all of the grown-ups in the universe. Then, who is paying for the expenses of Ash, the gym leaders, or Jennies or Joys?