"Complicated. As best we can tell, pokémon know roughly where human routes through the wilderness are, and the ones that spend time on and around the routes overwhelmingly tend to be the ones that either are curious about humans or want a fight for whatever reason. The ones that lurk the routes almost always understand some human languages, and usually engage trainers if they're interested. I can't speak for everyone, but I plan to talk to any potential capture first, and let them go if they're not interested."
Then she shakes her head. "Sometimes there isn't a choice. Sometimes there's a disaster, and someone — human or pokémon — could get hurt or die if you don't battle and capture a rampaging pokémon. The polite thing to do there is offer to let it go after, but sometimes that can't happen, and sometimes it could but the trainer doesn't want to."
She sighs.
"I'm lucky. I can guarantee I'll be understood by anything but a dark type."