All I have to say on the matter is hopefully, no more dang Steel types. The freakin' most impervious type since Generation 2! What were they thinking? It was hard enough dealing with Ghost and Rock types. Fire+Psychic; I'm up for it, but let's have some more pokemon of the general types that there were the least of in the previous games.
Ninetails isn't fire/psychic. And f/p is a rare type combination.
What annoys me is when a type combination that wasn't previously seen before then becomes so common to the point of blandness.
Take Water/Ground. Was unique to Gen II, but then Gen III came along and added, I think, three new Water/Ground families. Then Gen IV came and did the same. And now so many Water types have Ground typage as well that it's kind of annoying.
Same, most infamously, with Fire/Fighting.
And same with Fire/Psychic: not seen before Gen V, but Victini and Darmanitan both share it. I hope Fire/Psychic doesn't become overly common in Gen VI.