In Marvel and DC Comics' Avengers/JLA crossover, the Flash used the high stakes of the Infinity Gauntlet to be faster than his Marvel counterpart Quicksilver. However, it wasn't just Marvel and DC's heroes who came together and met face to face. When none other than Darkseid gets his hands on the powerful Infinity Stones, Flash runs as fast as he can to intercept and contain one of the most powerful weapons in the Marvel Universe.
In Kurt Busiek and George Pérez' Avengers/JLA, DC's Krona and Marvel's Grandmaster meet, deciding to play a cosmic game of epic proportions and using the heroes of their respective universes as their pawns. In order to win, the heroes must collect 12 items of power (six from each universe). While some heroes such as Batman and Captain America work together to understand the true nature of the game they are all forced to play, the majority of the heroes begin brawling with one another across their universes, seeking to collect more items of power than the other team.
As a result, Avengers/JLA #2 sees the Avengers and Justice League duking it out in the continuing struggle to obtain the various items of power. While Wally West's Flash has already proven himself to be faster than Quicksilver by stealing the Evil Eye of Avalon from his grasp, he doubles down when the Infinity Gauntlet is at stake. Traveling to the hellish world of Apokolips, it is revealed that the Gauntlet has come into the possession of Darkseid himself. Thankfully the powerful weapon is only workable in its own universe, making it worthless to the cosmic conqueror. As such, once he discards the Infinity Gauntlet the race is on for Flash and Quicksilver.
While the heroes are teleported before Darkseid's Omega Beams destroys them all, Wally is able to grab the Infinity Gauntlet, beating Quicksilver yet again. This made the score 6 to 5 in the Justice League's favor. After a brief tie where the Avengers gain the final item (the Cosmic Cube), Batman and Captain America ensure that the Justice League will be the ultimate victors, which resulted in both universes being merged by the Grandmaster. Regardless, the massive crossover of heroes is the perfect opportunity for Flash to prove himself against Quicksilver where the Infinity Gauntlet become an incredibly powerful and motivating finish line.
While Quicksilver might manage to get the Cosmic Cube away from Wally later on, it is only because Flash's connection to the Speed Force has begun to fade due to the final battle being held in the Marvel Universe. Seeing as how Wally wins two items over Quicksilver, it does seem as though he's still the clear victor overall. Regardless, the fact that The Flash won a race for the Infinity Gauntlet itself is a pretty major feat, supporting the idea that Wally West may be the Fastest Man Alive in both the DC and Marvel Universe.