You can see the attention to anatomical and scale flow detail here. I thought it would be cool to use elongated scales instead of feathers. This sounded a lot easier to pull off then it turned out, there was a lot of drawing and redrawing here to get it right.
I was really charmed with the concept of taking a small cute mammal Pokemon and having it eventually evolve into an oceanic macropredator. What better choice for this than Vaporeon?