First and most importantly, get rid of the backgrounds. They're uber distracting and make my eyes burn. Ahhh the burrrrrrn XD jk.
For the sprites, Zangong is well down, the headis well blended but the body looks rather awkward. Mostly the tail.Its just kinda funky. Blended well,but funky.
Crystal is just plain creepy Oo
Pikatata is verry well done. Its blended quite nice but the colors are rather dark. The head was meant for a guy, not a girl, so she looks like Norman cross dressin. You need more diver outlines too. *nods* Anyways, nice sprites pretty much. ^^