>>55086493You can start Teal Mask as soon as you get to the academy I believe - or at least at the very beginning of the treasure hunt.
The scaling was an odd choice, but better than nothing: You can play through the dlc post game with high level encounters/battles, or start early where it seems to be levelled around you having just started on the treasure hunt and then ramping up from there.
For example, your first named trainer battle will be around lv 12-13 or lv 60 with no in-between. If you didnt want to be hopping back and forth between the dlc and main game, I started and beat it about halfway through the main story, and that felt pretty natural with the levels of bosses/legendary pokemon you encounter/catch.
Only other thing to note is that both dlc expand your options in clothing shops/hair salons back in the main game so long as you beat their first story fights. Not a big deal, but if you weren't sold on the base game stuff then there might be something there worth looking through. There's almost certainly youtube vids of people running through all dlc clothing options.