Big head mode: 
Get 30 licenses in arcade mode with any 
character. Then press Square + X at the
character selection screen.


Hard mode: 
Get all 36 licenses in arcade mode under
normal mode. Then press Circle at the stage
selection screen.


Bonus Boards:
If you unlock hard mode, then play a level 
until you get all of the licenses for that 
level and for every level you do this, you 
will unlock an extra board.