As with most other commenters on this piece, I too see artists going either all draconic or all insectiod with their designs. This piece however is a good balance between the two, and I must say I love it to pieces. Realistic headcanon accepted!!!
It's wings should be a little bit bigger and wider in order to realistically support it's massive weight (at least as big as it's body, like the official Pokemon sketch), but other than that, it looks amazing!
The wings are actually more or less the same size as the one shown in the original anime drawing (which, under scrutiny, may not provide flight on their own. Wing beats per second, and other biological structures such as hollow bones also come into play).