As for people saying Ghost and Dragon-types should be rare, I respectfully disagree. The rarity of a pokemon should be based upon how high its stats are, not its typing. For instance, uber-tiers would be the rarest of all because of their very high stats and learnset potential.
The kinds of pokemon I want to see:
-Pure Flying, Ice, Rock, Ghost, Dragon, Dark and Steel-types! These types only have a few single-typed pokemon, while Flying has none.
-Another dual Grass/Dark-type! Nuzleaf/Shiftry or Cacturne are just poor excuses as neither of them have a physical design that makes them appear as if they emphasize the dark arts at all. A grape/berry pokemon line would be much better, as most berries in real-life have a natural dark coloration, or something like Youko Kurama's ojigi plant from Yu Yu Hakusho.
-A non-reptilian Grass-type starter line for once. I thought reptilian characteristics are suppossed to be representative of the Dragon-type.
-More Bug, Grass and Poison-types with at least decent stats.
-More pokemon based upon inanimated objects.
-New type combos that haven't been done before.
-An alternative evo. line for Torchic, so we can one dual Fire/Flying-type that isn't either reptilian or a legendary.
-Some actual ???-type Pokemon. There are already some existing Pokemon, like Ditto and Arceus, who sound like they can fall under that category.
-An Agahnim lookalike. Nintendo owns this character, thus they easily make a pokemon out of him. Probably could another pure Dark-type legendary as well.