This is a good point, and a widely made misconseption. If anything, it's Kingdra with the adventage in the match up. Why? Because Luxray 2HKOs Kingdra for 2 energy, and Kingdra 2HKOs Luxray for only 1. Not only this, but a Claydol dies in four turns, slowing you down a bit. Furthermore, Kingdra generally can attack T2-3 almost every game. Luxray cannot do the same, it needs more back up, or set up, however you want to put it. Sure, Luxray may get an occasional 1HKO, but it can't make up for every 2HKO Kingdra has been unleshing all game.