In any case, I don't see the point in nerfing them just for the sake of bringing them to the same level as the others. I think they should retain their powerful status because the beauty of this is that they are more powerful than the average Pokemon or Legendary, making the player feel powerful for having them. If they are not as powerful as they look, that's bad because they lost the appeal. Golurk
, for example, while not a Legendary, seems underwhelming because despite its size and stature, it's not quite as powerful or sturdy as it looks (but I still love it anyway). Maybe if you want, you could lower their level to a more manageable state, but there are a can of worms involved, like setting an appropriate level for them, and Arceus
(because it is available at only Level 100).