Press the start button at the Title Screen.
You will then be taken to the difficulty select screen.
Choose your difficulty, and press and hold all four buttons(A,B,X,Y)on the Wii Classic Controller at the exact same time.
You have now unlocked "red blood" and "more violence" aka cutting opponents in half.
There is no chime or audio cue unfortunately, and I always just sit through the "How to Play" Tutorial and it will show the blood color.(It should be red if the code was executed properly)
|Press ABXY at the same time on the difficulty select screen||Red Blood, More Violence|