If the opponent could search the world and pick the biggest toughest 5 year olds the answer would be fewer than most anyone said. The most unrealistic requirement is that the 5 year olds aren't afraid. If they were physically 5 year olds, but mentally Green Berets, it wouldn't take that many of them. Ten large fearless 5 year olds that jump on you simultaneously and start biting and trying to grab and bite your nuts would be very difficult to deal with. Ten more in reserve would probably do just about anyone in. If they were a real group of 5 year olds, you could use your deepest, loudest, meanest voice and yell at them and they will throw in the towel.