The player is faced against Fox and Falco on the Lylat System: Venomstage, but Fox and Falco are both equipped with a permanent Cloaking Device. As a result, they are more difficult to see. Although they are invisible, Fox and Falco can still be damaged, akin to an Invisible Melee.
This event it is still playable when unlocked, regardless of whether Falco has or has not been unlocked. However, if you beat this event, this event does not unlock Falco.
At the beginning of the match, Slippy calls up and says "How's the cloaking device I invented?".