The 1.1.1 Smash update has 3 empty character slots and 4 (2 Ω, 2 norm) stage slots, an increase of one each. Neat.
I'm still not sure why they use that "Tikibuzz" pointer for their empty strings. Also I made a mistake, there's 6 stage slots.
Not sure why there's one empty slot between the Mario Maker stage and the Duck Hunt one though. Maybe something wasn't done yet. ¯\_(ツ_/¯
The Marios are the character placeholders while the Tikibuzzes are the stage placeholders. There's 2 stage placeholders for the normal stages & 2 for the Omega variants. For reference, there were only 2 character placeholders prior to this update. As for the third set of stage placeholders, those could have been for Pirate Ship. Take these for what you will.