Dr. Gero sends Android 16 into the past so he can fight a younger, weaker Goku. Android 8 tries to protect Goku and Goku tries to help Eighter. Goku is then hurt, making Eighter go in an angry rage, damaging #16 and making him unable to fight.
Dr. Gero has just completed his latest Android creation, Android 16. Using the located Time Machine used by Trunks to go back in time a warn Goku and the others about the coming android threat, Dr. Gero sets the coordinates to the past when Goku was a young boy. Dr. Gero built 16 with a signal objective, to eliminate Goku, no matter what age he is in Android 16 will be able to find Goku. Dr. Gero fires up the time machine and in a matter of seconds 16 finds himself in the past, his location being the Red Ribbon Army Base Muscle Tower. Luckily for Android 16, he was sent at the exact moment when Goku was fighting his way through the Red Ribbon forces of Muscle Tower. Before long Android 16 locates Goku, but alongside Goku is another Android who Goku rescued from destruction, Android 8.
Android 16 was ready to commence his elimination of Goku, but Android 8 refuses to let 16 harm him. Goku begs 8 to get away from him because 16 was obviously much stronger than he is, but 8 had an objective of his own, and that is to protect Goku no matter what. 16 soon realizes that 8 is an Android as well, but if intends to get in the way of his objective then he leaves 16 no choice but to terminate his functions. 16 does not want to harm Eighter but he was programmed to eliminate any obstacles standing in the way of his objective. Goku soon decides to battle 16 before Eighter is destroyed. For awhile Goku is able to hold his own in battle, but 16 would prove to be too big of an opponent for Goku to overcome. Eighter decides to get between the two before 16 kills Goku. But 8 soon understands that Android 16 really isn’t that bad of a guy.
16 still clings to the understanding of why he was created and sent back in time. But suddenly 16 realizes he is unable to use his true power against Eighter but yet he’s unable to detect any abnormalities to his functions. He starts to wonder if his thoughts circuits were somehow damaged during his battle with Android 8. The battle between the two androids continues, even though Android 8 himself hates fighting. But he still will do anything to protect Goku and Goku agrees with Eighter and feels the same way. Hearing this Android 16 becomes confused on whether Goku is a friend or foe.
Dr. Gero had dedicated his time to building Androids that would kill Goku and through trial and error he discovered something. When Dr. Gero combined his science and technology with Gout’s human heart and the ultimate android was born. But his androids made from nothing had unstable human hearts. Android 16 started to wonder if he himself was one of those failed works. Android 16 ignored his confused emotions and continued his battle with Eighter but Android 8 wasn’t holding back anymore.
Eighter rammed 16 which made him suffer severe damages to his head. Repairs were impossible and he was unable to continue his combat operations. Eighter checked on Goku and found out he was alright. But Goku was more worried about Android 16 which confused 8 because he was trying to kill him. Goku thought it to be amazing that there was someone out there that was so strong. Goku vowed then to train harder so that next time he would be able to beat him by himself. Goku even now realized that Android 16 wasn’t a bad guy. Android 16 is a machine not a person, but there are mysteries in this world. 16 soon realized that the cause of these emotions was due to his human heart. He looked forward to seeing Goku again.
Android 16 can be defeated by Goku or Android 8. If Android 8 defeats him before pressing the transformation button after switching from Goku to Android 8 then the dialogue will be different and Android 16 will be killed.
- This scenario bears great similarity to the basic plot of the Terminator franchise, in which an Android (a "Terminator") is sent back in time to kill somebody with an important role in the future. Coincidentally, Android 16 seems to be based on the Terminator, even sounding quite similar in the FUNimation Dub.