From SmashWiki, the Super Smash Bros. wiki
Mechanical Menace is a single-player event match in Super Smash Bros. for Wii U. In it, the player controls Shulk and must defeat Metal R.O.B. and Metal Mega Man in a stamina battle. When the stage darkens, Metal Face appears and the player must defeat him as well. The event must be completed before the sun rises after the dark phase. The player has 150 HP while the opponents have 200 HP.
This event is unlocked by clearing Unwavering Chivalry. Completing the event unlocks the up path.
Completing the event within 60 seconds awards a Shield Exploder Jacket equipment.