I would say that a generally active player is one who makes 1k - 2k clicks per day. Some users click 5k+ unique Pokemon a day, and the click exchange only gets you about 500-600 unique clicks. I'm usually clicking 4k credits a day now that I'm active.
I would describe that kind of clicking to be very active users. It doesn't take much more than half an hour or 40 minutes to click 1000 adopts(in you're using shift+click and ctrl+w in people's boxes), but that's still a lot of someone time if they have a busy schedule. Getting 5 and 7k clicks takes a few hours, at least.
That's just my own musing, though ^^