Obsidian Prophecies operated by the same general rule - battles ended with knockouts, not fatalities.  Whether or not one wants to inject a bit more pizzazz into the setting, fatalities just don't really belong in a Pokemon battle.

And yeah - anything capable of listening to, comprehending, and acting on abstract instructions from human beings would be sapient.  On top of the proof of a large number of Pokemon throughout the series (shut up.  You all watched it fifteen friggin' years ago too) which are actively able to communicate with people in spoken word.  'Sides - it's more fun to write when the li'l beasties can think on their own.