User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-4502434-20120605203050/@comment-3568461-20120606181003

I told you, they measure their power level with a scouter. They have a chart that shows how much hp should a monster be qualified as a G rank or low rank. So, they won't get mixed up. It takes just a few second for them to use the scouter before they crack it and yell "IT'S OVER 9000!!!!"