The challenge of Surgical Strike is that only headshots or critical hits do damage. This limits the hero pool by only allowing characters who can hit headshots.
Hero selection: D.Va, Orisa, Roadhog, Wreckingball, Ashe, Genji, Hanzo, McCree, Mei, Reaper, Soldier 76, Sombra, Torbjörn, Tracer, Widowmaker, Baptiste, Lucio, Mercy, and Zenyatta.
While some of these character sound great there is actually a downside. Roadhog's ult is the ONLY ult that can do damage in this challenge. Despite hitting the head McCree's ult is useless. Soldier ult? Useless. Hanzo's ult can do damage but only with the arrow itself, not the dragons. Torbjörn is the worst possible choice as his turret doesn't hit headshots making him a 0/10 for this.
Remember, this challenge requires the most skill in aim, and I can't help you there but I can give tips on who you can play to better help you and your team out.
Roadhog and Wreckingball are the best tanks for the job as they're good meat shields and if you don't believe yourself to have good aim these might the best choices but in the right hands can be very deadly. Ashe with B.O.B. makes a very good distraction for the enemy tanks but requires more aim than most. If you have a very agressive playstyle like me Wreckingball, Tracer, and Reaper are going to be your best choices as long as you hit your shots. Ana and Baptiste are both very good and luckily you don't have to hit headshots on your teammates with either so choose who you feel comfortable with if you decide to go healer. Zenyatta has without a doubt the most useful ult however you can only heal one person at a time. Decide with your team what you'd want.
A tip for the assassins. Wreckingball, Roadhog, Ashe, or any character with a boop ability will be able to buy more time to kill them which you want because if they do take someone down, amd they will, you won't be able to get them off by punching them, the whole team MUST shoot her off ASAP or you may find yourself attempting to revive a teammate in a stickier situation than before. Roadhog can pull assassins off of players, must have if your team is failing because of assassins. A Zen/Baptiste combo works absolutely well against the heavies. If you find yourself failing because of them try this comp out; Zenyatta, Baptiste, Roadhog, Hanzo.
Take your time, don't rush in by yourself and stick together and you'll be fine. This is the hardest of the challenges so it may take your team more than a couple tries. Just stick with what you feel works best for you and do your best to keep everyone alive. Remember: you have time to revive fallen temmates, if you need to run do so.
If you would like help for this challenge and don't have anyone to do this with message me on Xbox and me and some discord friends will happily take you through.
My teams setup:
Wreckingball, Baptiste, Hanzo, Ashe.
Alternate setups:
Roadhog, Baptiste, Hanzo, Zenyatta.
Roadhog, Baptiste, Orisa, Zenyatta.