User blog:Blinkn/How does Flash fight?

I haven't really ever read a JLA or Flash comic and I've only ever seen him on cartoons, where the speedster is often the class clown of the team, so how does Flash contribute to a fight?

What can he do against a villain like Sinestro, Darkseid, Metallo, Parasite, the Manhunters, or Doomsday? The benefit of his powers against normal humans and some aliens is obvious, I'd imagine he could defeat most Batman's easily but what about the heavy hitters?