Jolteon's evolution might be an interesting fakemon, but not as Jolteon evolution (if you keep it like that) because it doesn't fit in the ''look'' of eeveelution by his style. Also, the Flareon's evolution looks too much like a ''long leg doggy head bigger Flareon''. In my opinion, all Eevee's evolution are suppose to look like a genecaly modified cat and no other animal/object.
Now, the technical issues for the first one are that the source of light seems to come from different places depending where you look. If the light come from infront of it, the back of his head should be more shade while if the light come from beside, his body shouldn't be that much shade. The second issue is that the head isn't in the same direction as the body. You should either change the orientation of the head or shade the neck to show that it turned its head ro the right.
The Flareon's evolution has 2 major issues. First, it seems to have flames on its head, middle long fur on its neck and a long fur on its tail. Choose one of those and stick to it because when you mix them it odd (doesn't look natural). Plus the fur on its neck appears to be thicker onfront thant on the sides. Second, the main problem with shading is the front legs. Look at Eevee and Flareon, both have the pale color on their front leg closer from us, so shall your. Also, its legs are long enough so that the bottom of them shouldn't be shade.