Very impressive.
Simply put, this Flash animation is phenomenal.
The art style was fantastic, utilizing many different colors and shades that made each pokemon look vibrant and alive.
The animation itself flowed very well and used many alternating extreme camera angles that gave the video a constant sense of action. You certainly have an eye for how to properly utilize these, and it shows.
Your effects are also some of the best I have ever seen. Each beam or ice attack shimmered and glowed enough for it to look realistic, but not be distracting.
The music fit along with the art style, a catchy but not overbearing theme that added to the animation without interrupting the video itself.
The story is not all that important, but it is nice to see that you made one anyway, it at least gives a sense of individuality to the characters, even if they are only fighting. I also enjoyed how you introduced the characters by panning over a double layered image in a very anime-ish style.
As far as negatives go, the only thing I could pick at is how it is quite short, and that the health bars depleting was a bit much when multiple enemies were killed. (This looked fine for Steelix and the individual enemies, so I will assume you just wanted to be consistent)
Congrats on front page, and good luck on your next animation, original or not, I am sure it will be great.