I don't think any of the Mario Pary games ever let you set it up with all computer players. (I've got 1-3 & 7 and played 4.) The game detects the number of controllers and let you set up 1-# controllers for human players.
heh, you're kind of responding to the "wrong" entry, but still...
in 1-3 and... one or two of the GC ones, you had to start a game with one human player, but you could then set that human to COM control, and it would do the "right" thing in terms of info screens that any player, but at least one, had to respond to.