The Piplup Family
As usual, the water starter is an amphibious vertebrate, and unless you count the inexplicably flying-type Delibird, which does appear to be penguin based, Piplup would be our first proper pokepenguin.
The second stage, Prinplup, suffers the usual forgettable middle-stage syndrome, and in particular, I seem to have completely forgotten the name "prinplup" until doing this review. I had a "THAT'S what this is called?" moment and I don't even know what I thought it was called. Sorry, Prinplup.
The final stage, Empoleon, is a surprise water/steel type, and it's a pretty interesting idea to have a metal-plated, regally dressed, amazingly dangerous looking giant penguin, but this is another of those pokemon I feel is a bit too detailed. I think it's the blue parts that bug me the most. It's never quite AS messy as I remember it, at least, and either way, it's a menacing penguin, as nature truly intended.