>>53643770In the wild, they eat predatory, territorial, hazardous species. Young members of the Ralts line are encouraged to intentionally enter the territory of dangerous Pokemon species in the hopes that they'll be attacked. They're told that when they're being attacked, experiencing fear and pain, they should imagine themselves as a human they're being trained by. This typically activates their protector instincts, giving them the strength needed to kill the attacking Pokemon, which they then eat.
This serves two purposes. First, it eliminates members of the line with weak protector instincts from the gene pool. Second, it gives the Pokemon life-or-death combat experience and acclimates them to death and killing, making them a better protector.
