So here's another video regarding character slots. Some of it is information Source Gaming gave us, but some of it is new, I believe.
The TL;DR is basically this:
- CSS Slots (29/30) were apparently removed altogether
- WoL Slots (originally 16) had 2 slots filled by Joker and PP, then two more added for Hero and Banjo. There are still 14 placeholder slots left (12 post pass)
- The "attack" strings in the code (also 16), apparently had 4 of these occupied by the DLC so far, leaving 12 remaining slots (10 post-pass)
My personal guess is that the "attack" strings are being filled in order because they correspond to the order the characters were implemented, but the WoL slots could be ordered differently due to other development reasons (remember, we got VR mode before HRC, even though HRC came first in the numbering order of Games & More modes). I think that depending on how things go, we might see two more slots being added to the "attack" strings in the future.