It's Monday, which means that Sakurai's back to deliver a new screencap of the upcoming Smash Bros. 4!
Today's screenshot looks seemingly boring by all accounts...But in actuality...
No wait, it is pretty bland and kind of a waste of a day. Darn.
But no! I KEED! In all seriousness, it's what Sakurai himself has said with the reveal of this shot that makes today's update decently interesting.
Here we see AC's the Villager and Kid Icarus' Pit looking into the background at Wily's Castle. But why in particular? Because they're keeping their eyes peeled out for the stage hazard in the form of the mini boss Yellow Devil, seen here in this update last week!
So that answers that little mystery of what the Mega Man boss was doing on the stage. Previous guesses included that he was a boss for either an Event Mode trial or Adventure Mode styled romp.