Play as Ushi the Cow
Enter the ‘Rodeo Mode’. Hold on for a minute or more in the ring with the cow and he'll become selectable.

Play as the Joker
To get to this character you must win all 100 fights of the ‘Survival Mode’.

Play as Master
You must beat all of the ‘Master Challenge’ fights.

Change Outfits
To change your uniform, hold R while choosing your character.

Play as Boro
The easiest character to get, you can also get to him by beating the game on Easy.

Play as Rob the Robot
To play as the practice dummy, go to the ‘Fastest Mode’. Beat all three characters in less than a minute and you can get rob.