###I covered part of this in my answer regarding "How does the Flash perceive time?" In the treatment I discuss that the nature of the Flash's powers are based around his ability to perceive, analyze and counter the attacks of his enemies.
I covered part of this in my answer regarding "How does the Flash perceive time?" In the treatment I discuss that the nature of the Flash's powers are based around his ability to perceive, analyze and counter the attacks of his enemies.
Despite their silly names and often less than stellar outfits, the Flash's Rogues Gallery are not to be taken lightly, especially when they are working in concert. The bulk of the Flash's Rogues Gallery use weapons, techniques, or abilities that attempt to confound, distort, or alter the physical properties of the world around the Flash in an effort to prevent him from maximizing the use of his powers.
For example:
Boomerang, Mirror Master and Trickster use misdirection, physical distractions or optical illusions to keep the Flash from being able to perceive attacks until they are too late to be avoided.
The Weather Wizard, Mr. Element, Captain Cold and Heatwave use physical environmental attacks that alter the battlefield or can affect the Flash directly using heat, cold or electricity.
Professor Zoom, Savitar and to a lesser extent, the Top were able to compete with the Flash directly using powers similar to the Flash himself.
Gorilla Grodd and Abra Kadabra used advanced super-science to challenge the Flash's speed-based powers.
The Flash is not completely invulnerable to injury even when agitating his molecular structure while under attack. Most normal physical attacks will not harm him, but many of the specialized attacks of his Rogue's Gallery may be able to damage him incrementally. The other issue in using intangibility is the inability to hit his opponents.
His ability to predict the future is simply him attempting to figure out what his enemies will do based on what they have done in the past. If they are able to distract him or confuse him, his ability to predict their plans may be distorted or even neutralized.
As far as time-travel is concerned, his ability to affect a circumstance once he has been involved in the event is limited and would likely cause a temporal paradox as he could not be in the same place at the same time, even though his powers allow him to alter many of the laws of physics, he tries to avoid creating paradoxes since their effects on the time stream can be unpredictable.
Is the Flash formidable? Absolutely. But the Rogues are a very unusual group of villains because they are pretty exclusive in their efforts to both coordinate and cooperate in their fight/grudge against the Flash. Their hatred was so great once they even transcended death to return to plague the Flash; that kind of hatred is an advantage no matter how fast your opponent is.
