Sometimes the enemy team can help you. A D.Va player got a great team kill with his ultimate. But it wasn't because of them. Reddit user A-Stupid-Monkeyyrt posted a clip of the moment to the Overwatch subreddit. At the beginning of the video, they were setting up a D.Va bomb atop a ledge at Watchpoint Gibraltar. Passing under their load, they lowered their ultimate into the chamber. It's hard to see what would happen after a first-person perspective, but the bomb killed all six members of the opposing team.
The actor then flipped the video from the reverse angle to third-person slow motion. When D.Va launched their grenades from the ledge, they landed near the payload. The enemy Reinhardt lifted his shield and could have prevented most of the damage if the enemy Roadhog hadn't hooked the bomb at the last second, pulling it behind Reinhardt's shield and wiping out the entire team.
As commenters noted, Roadhog probably instinctively wore the bomb to shove it away from their team, but they got the angle very, very wrong. One of the best D.Va strategies is to launch his grenade from above or from an unseen angle to land on the opposing team and give them less time to flee or hide behind a Reinhardt shield. Fast to draw, roadhogs can attach the grenade and push it away from the team, saving them from most of the damage. Unfortunately for this hostile team - and fortunately for A-Stupid-Monkeyyrt - the opposite has been the case.