I'm a big fan of the old Pokémon artworks you can find on the first series of Pokémon cards.
I also really like the first official images released and of course the old sprites of the first generation where some Pokémon didn't quite look like their final versions do today.

Vaporeon is a very good example of going through some design changes in the very first years of the franchise. Especially the sprite found in the green version only released in Japan had some noticeable details it lost over the years.

I tried capturing those blending them in with my art style and a sprinkle of artistic freedom.

I absolutely dig the old design of its back fins and how they used to be connected with the fin on its head.
This makes so much more sense in terms of hydro dynamics than that big umbrella shaped thing around the whole head it has today does.
I wasn't sure about the stripes on the body. If they were meant to be markings or some kind of shading, but I decided to go with markings :)