Dark isn't quite the right word. Asians, in general, have a laxer view of how animals can be treated, so stuff like taming wild animals with a whip isn't considered particularly dark or objectionable for children. Of course, once Pokemon got big in the states, implied rough treatment became a no-go.
Funny thing is, the anime had an episode that addressed the whole whipping thing and it was ultimately portrayed as a valid training method as long as you genuinely cared about your Pokemon.
