The image itself is very balanced. Blitzle is centered, and is obviously the focus of the image. In terms of color, the mottled blue background works well to set Blitzle apart. One nitpick is the cleanliness of the lines; There are a few spots where smoother lines would have enhanced the pokemon ‘just’ a bit. But thats me being fairly picky in this case, it doesn't necessarily detract from the image.
Blitzle is quite accurate, nice light shading that isn't too sharp. Would have been nice to see a custom pose. Also would be better if BLitzle had been in some sort of action, or given some reason for being on the bridge and not posing for a picture.
Theres a lot of nice elements going on here. I like the background and its misty, clouded appearance notable of some of those caves. It would have been nice to see some vague, indistinct shapes either looming or floating in the background, giving a better sense of scale to the image. A part of this image that I really like is the bridge. You gave it a nice appearance of an aged yet sturdy structure, and it definitely blends into the image well.
One part that did not seem to fit as well was the lighting of the image. The straight-down light source does not seem to fit with the cave setting you have aimed for. Something more fitting would have been perhaps a colored light source similar to the crystals found in the cave, or some visible light source in the image itself. Another part that felt out of place was the sparks assumingly sent out by blitzle. The method they were drawn gives them a closer appearance to glowing confetti. Maybe sharper, white pieces with a yellow glow could have given the desired effect, or something different altogether.
In conclusion, I think the overall quality of this image is very nice, and with a few minor improvements as listed above, it would be a perfect image.