Smash Dash is a mode exclusive to Super WageGannon6 Bros. Brawl. The mode plays very similiar to Battle Run and Mega Run.
Link to the game's main page: universe-of-smash-bros-lawl.wikia.com/wiki/Super_WageGannon6_Bros._Brawl
In Smash Dash, players must race to the finish. While facing enemies that get in their paths, pick up Power-Ups in a similair manner to Mario Kart and Battle Run, in which can be used to take out enemies or opponents while playing on the map. Traps are also placed on the maps in Smash Dash (Ex. Spikes, Dead Ends, etc.). The Power-Ups that are picked up can take out other players. If a player hits one of the Power-Ups used by another, they are instantly knocked out and they respawn after a few seconds and they continue the game. Once all 4 players have reached the finish, the game is over.