No, Flash could not solo the Avengers. Even with his superhuman speed, Flash would be outmatched by the Avengers whom are comprised of some of the most powerful superheroes in the world. The Avengers roster includes Iron Man, Thor, Black Widow, Captain America, Hulk, and many others who have vast superhuman abilities.
While he may not top many lists as the Most Powerful Avenger Ever, Iron Fist once proved he could take down the entire team on his own.
While it is fairly obvious that the Flash could run circles around Thanos under normal circumstances as his powers make him virtually untouchable, there wouldn't be much the Scarlet Speedster could do if he was around for Thanos' Infinity Snap as there is no way to outrun the god-like power of cosmic chance.
He's literally one step ahead of Scarlet Witch. End of Story. THE FLASH wins! He's ability to see INFINITE POSSIBILITIES before they happen not to now talk about his Speed Force warning ability of his Opponent gives him the ability to negate all of Wanda's powers.
QUICKSILVER. If you know, DC's Flash character uses Speed Force to run at lightning speed and on the other hand in Marvel Universe, Quicksilver is a mutant. During Marvel/DC crossover, Flash was not able to tap into speed force, hence losses his fastest speed. Hence Quicksilver outrun him in the race.
He can travel through space unharmed and can summon powerful bolts of lightning with his indestructible enchanted hammer. The Flash may be able to escape harm for a bit, but in the end, Thor would be too strong for the Flash to withstand.
Despite being surrounded by Thor, Iron Man, and Wanda, Black Widow is one of the most valuable members of the Avengers team. In one of the recent Marvel issues, Natasha Romanoff has proved that she can easily beat The Flash from DC.
Overall, The Flash is among the most powerful superheroes in DC Universe, and even though Quicksilver is powerful as well, his abilities don't come anywhere near those that Wally can throw at him. In a battle between Flash and Quicksilver, Flash would win.
The Scarlet Witch's magical abilities are simply unmatched by the other Avengers. DC's strongest hero is generally agreed to be Superman, who can take hits from just about any villain in the universe and dish them back 10 times harder.
10 Would Lose To: The Flash
There's really nothing Hawkeye can do to hurt the Flash. He can move much faster than Hawkeye can shoot or just vibrate his molecules to let the arrows go right through him.
In a competition of speed between the Blue Blur and the Scarlet Speedster, it will take more than math and science to really comprehend their overall speed. However, taking all things we know into account, Flash would win a typical race against Sonic the Hedgehog and come out as the faster of the two.
No Avenger could really beat the Flash because he is incredibly fast, able to move at light speed and run on water, making him nearly impossible to outrun.
Hawkeye. Clint Barton is likely one of the first characters that come to mind when the subject of superheroes without powers comes up. Despite his lack of powers, Hawkeye might be one of the most dangerous members of the Avengers.
Thor. Blessed with the powers and long life of a god, Thor was undoubtedly the most powerful member of the initial version of the Avengers. Not only can he fly and transport between worlds, but he was also the only one capable of taking down Thanos, even after he had assembled all six Infinity Stones.
Even with the best laid plans, if the Avengers are smart and stay together, there's pretty much no way that Batman can win against them- at the end of the day, as smart and prepared as he is, he's just a regular human against some of the most powerful heroes around.
Wally West is the Fastest Flash and is arguably the fastest being that has ever existed, as said by Max Mercury—and it has been remarked that Wally and Barry are the only two speedsters that were fast enough to even outrun death itself.
When Barry got his Tachyon device, he was running faster than Zoom, who was over 4x faster than Barry's fastest ever speed. Which is obviously faster than we've seen Reverse-Flash. But Barry was never able to catch Eobard when he was running (excluding his past self) so we've never seen Reverse-Flash at top speed.
But for the results on record, Wally is the clear winner. As we can see from the results here, the common folklore compromise that Superman can beat the Flash—any Flash—if he's allowed to fly in the race doesn't actually seem to bear any truth.
The Flash Would Run Circles Around Black Panther
Nothing Black Panther could do would help him against the Flash. Any attack could be vibrated through and while T'Challa is much smarter than Barry, Barry knows how to use his speed as a weapon in ways that would give Black Panther a run for his money.
In all cases, Thor reads about twice as fast as Flash! In the context of a physical race between the characters, the difference in speed is more interesting. The Flash travels at ludicrous speed, let's say realistically at the speed of light or 670,616,629 miles-per-hour.
The Flash's Speed Would Overwhelm The Wall-Crawler
The fight might be close, but Spider-Man would have a difficult time slowing down the Flash enough to beat him. Spider-Man definitely has a chance to land a few good blows, but the Flash is just too fast and unpredictable for him to beat.
That isn't to say Ultron is completely outmatched by The Flash, as the latter might also not be able to put a dent in Ultron's adamantium armor. Still, The Flash doesn't have to harm Ultron in order to defeat him, he could easily just tap into the cosmic treadmill and erase Ultron before the robot was even created.
Only if the battle is under water. Aquaman is strongest of all when under water, even flash can't move faster than aquaman. But if they're fighting on surface then it's a easy win for flash.