Its not sports drinks that dehydrate you, its energy drinks that contain taurine and caffeine that can have a diuretic effect.
Things like power/gator-ades are isotonic, meaning they replace fluid salts and minerals lost in perspiration, though unless you are undergoing intense endurance training, the benefits over good old fashioned water have been proven to be marginal at best.
As to 'dropping potassium', has that been medicaly proven? because if not, it is unlikely to be the cause of any symptoms you feel you experience. Excess potassium can impede heart function, so be careful.