Gen 5s might have a better advantage compared to older builds cause the abilities like Regenerator and base stat tables are more optimized. Them not existing once you notice is a little jarring though I agree they should be implemented eventually
Right now the only way to hear variety music (such as battle tower themes) is playing randoms PVP queue. There should be a dropdown for your overworld duel theme song and other options for NU/UU/OU battle themes instead of only 1 song for all those modes.