Kaioken

Kaioken is an unlockable form that is accessible to all races. Along with being able to be used by all races, it can be set from 1-20, meaning a user can have Kaioken x3, or Kaioken x20. Kaioken x20 changes the hair color of the user. It can not be customized by the Custom SSJ Gamepass, and can not be used on top of other forms. 
To unlock this form, you must go to Snake Way in Otherworld and teleport to King Kai's planet. Talk to him and unlock Kaioken, along with Spirit Bomb.