I like a lot of Pokemon from 5th gen, but the one that comes to mind immediately is Mienshao. It's beautiful AND powerful. What more could you ask for? I love its color scheme and design a lot, plus I really like weasels. It even has a nice name! Not only is it one of my favorite 5th gen Pokemon, but it's one of my favorite Pokemon of all time.
Not only that, it gets some really cool abilities in my opinion. Plus, it gets moves that complement them nicely, like U-Turn+Regenerator and HJK+Reckless. Inner Focus isn't bad either, because it basically just gives Fake Out users the middle finger.