Obtained: Speak with Raditz in the East Ravine Area after using the Dragon Balls to revive him
Objective: Defeat all enemies
In order to fight Raditz again you will need to collect all seven of the Dragon Balls and use your wish to bring him back. To locate him, head to the East Ravine Area where his ship crashed. Speak with him as Piccolo to begin the battle (you can change player characters in the party menu). Defeat Raditz to complete the story.