Alright, thread is a couple days old, but I figured I should point this out:
Reusing the base poses from D/P/Pt/HG/SS is not Game Freak being lazy...it is Game Freak being pratical. Think about: There will most likely be well over 600 Pokemon(including alternate forms and events) by the time this Generation ends. Game Freak is making sprite for idle poses, hurt poses, probably attack poses...the list goes on. Not only that, but as we have seen from videos, they are fluid animations. I figure they could be making at least 15-20 sprites EACH for a Pokemon(obviously, fewer for some mons and more for others). Probably even more. Meaning that they are making well over 6000 sprites(could they reach even over 9000?!) just for the battles alone. Also, Pokemon sprites appear to be made pixel by pixel as opposed to being drawn and then put into the game. That is a very unreasonable amount of work GF is putting into this game, given that this was probably being developed at the same time as HG/SS was nearing the end of its development period.
Now, if faced with that amount of work, wouldn't you reuse past sprites as well?