Has it been confirmed whether the final boss is unlock-able? I haven't fought him yet, but I think it would make sense given that there's currently two random character buttons on the selection screen. Presumably he'd unlock after beating arcade with every character at a certain difficulty.
In any case the code is mostly there, just need to hook up the buttons to attacks.
"The combustion part is fine, it's the spontaneity that I have a problem with."