Dragon Ball Z (and Dragon Ball Super) explained what became of the Z-Warriors in Trunks’ post-apocalyptic future. Not all shared the same fate.
Future Trunks comes from a version of the future where the Earth was devastated by the ruthless killing sprees of the two androids. It was because of the androids Trunks had to use Bulma’s time machine to come to the present and prevent them from emerging. Thanks to Trunks’ warnings, the Z-Warriors were able to properly prepare themselves for their arrival, but a few big changes occurred on account of Trunks’ tampering with the timestream, with one of the biggest being Cell following him from the future to absorb the androids.
As explained by Future Trunks, his timeline’s version of Goku returned from space sometime after beating Frieza and contracted the heart virus, a lethal disease that took the lives of countless number of people on Earth. Despite all his power, Goku lost his life to the virus. His allies would have wished him back with the Dragon Balls, but that couldn’t work since he had died a natural death.
2. Majin Buu
In Dragon Ball Z, Majin Buu was separated into two beings, with one side becoming an innocent but incredibly powerful ally of the Z-Warriors and the other a force for evil. After getting loose, the evil Buu eventually destroyed the whole planet. Interestingly, that’s not at all what happened in Trunk’s timeline, despite the fact that his Earth only had one hero protecting it. In Dragon Ball Super, it was explained that Trunks managed to avert the Buu Saga from happening altogether. In contrast to the Z-Warriors, Trunks killed Dabura and Babidi right away. Due to his actions, Buu was never released from his prison.
3. Future Trunks
Following their defeats, Trunks became the Earth’s sole protector but found himself overwhelmed against the strength of Goku Black. He worked alongside an army of humans whose goal was to resist Goku Black, but it wasn’t until Trunks went back to the future to recruit Goku and Vegeta that they were able to stand a fighting chance. Despite having their help, Zeno had to intervene and destroy their timeline so that they could finally be rid of Zamasu. Thankfully though, Trunks still received a happy ending. Zeno used his abilities to recreate his timeline.
4. Master Roshi
Master Roshi wasn’t among the Z-Warriors mentioned by Future Trunks when he talked about the fight with the androids, but the Dragon Ball Z: History of Trunks TV special did touch on his role. He started to get involved, but Puar and Oolong convinced him to stay out of it, which would mean that he could still be alive somewhere. However, it’s worth noting that this may not be canon since History of Trunks conflicted a bit with the details of the androids’ battle with the Z-Warriors in Dragon Ball Z. Even so, Roshi choosing not to fight does make sense, especially since his power level was believed to be significantly lower than all other Z-Warriors. It wasn’t until Dragon Ball Super that Roshi finally got back into the action.
It was also Gohan, who grew into adulthood, transformed into a Super Saiyan, and became Trunks’ mentor. He spent 13 years keeping what was left of the Earth’s population safe from the two androids, but didn’t possess nearly enough power to take them down. In the end, Gohan died, leaving Trunks as the Earth’s last defense.
The same Dragon Ball Z episode that revealed the fates of Vegeta, Piccolo, Krillin, Tien, and Yamcha showed Yajirobe being killed by Android 18’s High-Pressure Energy Wave, but Dragon Ball Super ultimately retconned this event. When Goku and Vegeta had to return to Trunks’ future years later, they found out that Yajirobe didn’t actually die that day. After being saved by Korin with a Senzu Bean, Yajirobe survived in secret and later became a member of the resistance when Goku Black came onto the scene and plunged the world into chaos again. Though he maintained his reputation for laziness, Yajirobe stepped up during the Future Trunks Saga and put his life on the line to save Goku and Trunks from Goku Black and Zamasu.
One of the last Z-Warriors to fall was Yamcha. According to Future Trunks, the androids turned their attention to him after eliminating Tien. As a result, Yamcha was brought down by one of Android 17’s energy attacks.
8. Tien & Chiaotzu
Tien was the next to die after Krillin. He was attacked by Android 18, who shot a powerful energy blast clean through his midsection. His sidekick, Chiaotzu, wasn’t featured in Future Trunks’ flashback, but it was confirmed by the hero that he too died during the fight.
Vegeta and Piccolo’s death made defeat inevitable for the remaining Z-Warriors, considering they were the strongest fighters on their side. Krillin, who recognized how outmatched they were, attempted to make a getaway but was obliterated by a point-blank blast from Android 17.
Since Future Piccolo didn’t fuse with Kami, he was no match for the villains. He was easily killed by Android 18. It was actually his death that doomed them all, since his lifeforce is tied to Kami, the character whose power maintains the existence of the Dragon Balls. With them gone, and without Goku to visit new Namek with the instant transmission, it became impossible for anyone to ever be wished back.
Similar to his counterpart in the main timeline, Vegeta followed in Goku’s footsteps and managed to achieve the Super Saiyan transformation in the Future Trunks timeline. Unfortunately, it still proved lacking against the strength of Doctor Gero’s androids. Vegeta, who was strongest of the Z-Warriors in Goku’s absence, died at the hands of Android 17, thus making him their first victim.