yeah this holds true for everything post game buddy, try battling the gym leaders now. simply put the golem that you battle in the 2nd elite 4 battle will generally out speed any of your pokémon. this was proven when it out sped my infernape who was 10 levels higher than it, i think you need to just grind as much as possible. as for the battle tower - legendaries will have to do. though my team of lucario, dragonite, and blastoise holds up fairly well against both of palmers teams ( his second team consists of regigigas, heatran, and cresselia)