SSBU: The Key
Cloud finds a key in Master Hand's office while rummaging through his draws. He doesn't know what this key is for or what it opens. All he knows is that this key has a large dragon head on its handle. When Shulk goes missing near Mt Dragmore, Cloud realizes there's a lot more to that mountain then what it seems like.
SSBU: The Loop
Ness is locked in a time loop, he goes day by day trying to figure out how to tell someone without them forgetting it 10 seconds later. Ness is a puppet, being controlled by someone above. Who is pulling all the strings?
SSBU: Infiltration
There's an intruder in the mansion. This intruder is looking for a specific item and a specific person who owns that item. Can the smashers stop them before its too late?