I hope it's better than the Kanto Battle Frontier, which, imo, wasn't the best. They could've did so much such as allowing some of Ash's old Pokemon to appear and maybe giving Misty or Tracey an appearance, possibly even Gary. The whole saga was just so rushed, the same will probably happen with this one too.
Complaining aside, this saga could be pretty awesome. I'm hoping for:
-Johto Pokemon redemption. At least Totodile and Cyndaquil should evolve, Noctowl needs to be used too.
-Misty and maybe May appearing for an episode or two.
-Brock finally getting that long overdue farewell. His character is completely boring at the moment and he really hasn't done anything, or been interesting for that matter, for quite sometime.
-imo, I'd like the main group to be Ash, Dawn, Barry and Max, but I suppose that's a pipe dream.
-And then the usual, character development, interesting, well thought out fillers and some nice captures and evolutions.