No, you would not have done half with HP Electric. Are you even running damage calcs? Or are you just pulling these claims out of your ass? HP Electric has a base power of 140 (assuming you have HP Electric 70), as opposed to your STAB'ed Hydro Pump's base 180. So, HP Electric will do less damage than Hydro Pump. As for why I'm using a Careful Skarm, look here: http://www.smogon.com/dp/pokemon/skarmory. Scroll down the page and read.