Secret Smash is a co-op event match in Super Smash Bros. for Wii U. In it, player 1 controls Duck Hunt and player 2 controls Mr. Game & Watch and must defeat another Duck Hunt and Mr. Game & Watch in a stock battle on the Gamer stage. Both players have one stock each while both the opponents each have two. If either player gets KO'd, the event results in a failure. 5-Volt must be avoided at all costs since she can deal extremely high damage and knockback and can possibly deliver a one-hit KO.
Completing the event on the hard difficulty setting awards the player with the Springer Collar equipment.