I'd definitely like the Champion to be more of a challenge than more recent ones have been. (Diantha was the first Champion I ever fought where my Pokemon were overleveled; even without the Exp. Share and use of Amie that was the case.) Sure, they may pose as a humongous challenge to newer players, but I'd rather have their Pokemon be many levels over, have five-six flawless IVs (much like Cynthia's team), have good hold items (like the E4's and Iris's in Challenge Mode of BW2), and have the Champion's AI be plenty good. That being said, what I described may be better fit for Challenge Mode; regular mode would still make the Champion a challenge, but would likely tone down the intelligence of the AI, drop the held items (save for a Sitrus Berry or Mega Stone on the strongest Pokemon), and lower the levels. And of course, if they bring back Easy Mode the levels could be further reduced, making it easier for newer players.