Missed the first post so I'll comment on both here. Thunderyu looks pretty good overall, but a couple of things look odd to me. For one, his face isn't quite as expressive as it was before. One thing I liked about the old sprite was his weird little grin. I can see a little of it here if I look close, but I think what made the old one better was either the fangs or the look in his eye. Another thing is the gems on his tail. I can't really figure out where they're supposed to be placed; are they on the sides or the back? It seems like they'd be along his back, but that means the whole tail is twisting around pretty strangely. And the one gem that's closest to his wing is kind of angular, which I realize is unavoidable to get it at the right size, but since the highlight on it is suddenly much larger than it is on the others, it stands out a little too much and doesn't look like its a part of Thunderyu's body.
I love Volcaryu, especially his face. But, it's pretty bottom-heavy, although I might feel that way because I've been looking at the old sprite for a while. I think his chest could stand to be just a little larger. One more thing is the legs. His claws fully stick out, but there's no sign of his feet. That's not much of a problem with his left leg, but the right one might look better with maybe a bit of an outline where the foot would be. Otherwise, his whole upper body looks great. Can't wait to see how Polaryu turns out.