Clearly, (at least in the movies and video games), Fell beasts were powerful creatures and were deadly offensive predators, especially with the Nazgûl on them. They could choose either to bite their prey (less attacking radius but increased damage) or swoop down on them (larger attacking radius), scattering enemies apart or outright crushing them. If a Fell beast snatched a soldier, they could easily fly high into the air and drop their hapless victim to his death far below. Fell beasts were feared for their ferocity and speed, and were known as the fastest creatures in Middle-Earth since Smaug, the last great Fire-Drake.
Being a fully-grown dragon, Smaug was both massive and powerful, possessing physical strength great enough to crush stone with ease, as seen by his attack on the Lonely Mountain. He was able to fly thanks to his large wings, and had the ability to breath streams of searing hot flame from his mouth. Some comments in The Hobbitimply that his entire body was imbued with fire, as he was seen to glow in the darkness of the Lonely Mountain's depths, and his usual paths were said to have been "smoothed and slimed" (i.e. melted) by his passage.
Now i ask,Who would win? 3 Nazgul birds,Or smaug?