The third choice would be to steer them in a better direction altogether. If a fifteen-year-old is hellbent on stealing cars and barhopping, the responsible parent doesn't teach him how to make fake IDs and hotwire. ("He wants to do it so bad, I'll mentor him.")
Really, the kid sidekick is only slightly more wish-fulfilment fantasy than the adult super-hero, and only slightly more implausible. It's just where I happen to think the line should be drawn.