It comes from the show Sailor moon.
It refers to a villain in a series that has unlimited resources, vast armies at their command, godlike powers, and could steamroll over the entire planet in a matter of seconds yet ends up failing week after week to a relatively small collection of determined heroes.
Ex. The borg are a sailor moon villain, as are, I imagine, the villlains from Sailor moon.
ONce a truly great show, it loses some of it's entertainment value when you realize how effing misogynist the creator is. It used to be quite funny but now is reduced to issue of the week type storylines that use the fact that the show can be made in under a week rather than the 3 months it usually takes other animated programs to make it seemas though it is unusually insightful when in reality it is just really cheap. It used to be the big envelope pusher on TV but has snice been totally eclipsed by Family Guy.
Watch any episdoe dealing with women and tell me trey parker doesn't have deep rooted women issues.