Obtained: Speak with Android 20 near Darlinge Polynya in the North Mountains Area during the post game as Goku. You will need to use the Dragon Balls to wish them back.
Objective: Defeat Androids 19 and 20
Head to the North Mountains Area to find Androids 19 and 20 near Android 20’s destroyed lab. Speak with him to start a fight between them and Goku. Defeat both androids to complete the story.