Ooh. :0 All the Pokemon you've linked have really great color schemes that mix very very well. My only complaint is the possible overuse of either lines/scales or the color yellow in Haxorus. I can only assume you like the more kickbutt Pokemon from your choices, seeing as the immediate Pokemon all have claws, fierce expressions, and dark color schemes.
I kinda disagree with the "how far they've come" statement, however. Kanto had a lot of fairly simple Pokemon, the most detailed being like Omastar, Mewtwo or Venasaur. Unova Pokemon are a lot more detailed - especially with their dragon types. However, designwise, being more detailed doesn't make something automatically better. A plain teacup and a teacup with a doily under it is still a teacup; one's just more shmancy.
Also, Cohagrigus is kinda spooky, haha! But I can't deny it doesn't have a beast color scheme (why again can't I remember another Pokemon with those hues? It's a really good combo). The Pokemon as a whole, however, just reminds me of that one episode where Ash got possessed or something and it was really cheesy.
Note: Thank you.