Flashing Mach Punch
When the special button is pressed, the Brawler performs a short flurry of punches. If any of the punches connect to an opponent, the Brawler will unleash a barrage of punches, ending with an uppercut (hitting a total of 22 times if all hits connect). During the duration of the punches, if connected to an opponent, the Brawler gains invincibility. If shielded against, the move will not transition into the barrage, and if the opponent is buried, then only the first few hits will connect. Using this move in midair will momentarily slow the Brawler's decent. The move is somewhat like the Brawler's neutral infinite, except it is considerably harder to escape from and can KO at realistic percentages.
It is interesting to note that only one of the punches in the initial flurry needs to connect in order to begin the full barrage. In other words, if an opponent shields the initial small punches but drops their shield early enough for the very last punch to "tap" them, they will be hit by the full barrage. This can be useful for catching opponents by surprise.
This attack is possibly a reference to Zan Retsu Ken, an input attack that Ryo Sakazaki uses in The King of Fighters '94 and '95, where the attack is practically identical.