Looking pretty. I think the colored lineart and shading look both well executed. The only things that feel a little off to me would be the way the shape of the tail seems to change from left to right behind Vaporeon's back, as well as I feel like something seems off about the face. Like the right eye's iris position, missing eyelashes and how in combination with the nose and mouth part it seems like Vaporeon is making some funny face.
Would probably try redrawing the mouth and change the eye personally, but I can understand if you made a conscious decision to depart from that regular style Vaporeon face a bit more. the left eye seems good actually and I think it might help to shape the eye on the a bit in reference to the left one, in case you might think of doing some slight edits yet.
Oh, and there is a bit of a black spot remaining within the outline in the middle of the tail phin.

Seriously may revisit one day and do a redux. It was 5 years ago, and I think it aged well. :3

Yes, it looks really well. As said, just a littl bit of details that make the facial expression a little...excuse my phrasing...derpy. And as said, the tail got a thicker base to the right side where it seems like it's supposed to circle around the back of Vaporeon. <X3