Unfortunately the overlap between heroes who counter Zar and Bastion is not a lot.
Bastion is fairly easily countered by Sigma. Shield him and use the suck thing when he’s in turret form. It’s enough to outlast his turret cooldown. In the meantime, if he’s close enough (which he should be for his turret form to do proper damage) this should get you to the medium range you need to primary fire him to death. Your team will hopefully assist too cuz everyone hates bastion (I main him. I know)
Dva also counters Bastion because her DM and high mobility allows her to live through the turret form, protect her teammates, and then Bastion won’t be able to get away.
Unfortunately, Zar counters Dva and Sigma cuz her primary fire goes through their DM/Suck.
Unfortunately the overlap between heroes who counter Zar and Bastion is not a lot.
Bastion is fairly easily countered by Sigma. Shield him and use the suck thing when he’s in turret form. It’s enough to outlast his turret cooldown. In the meantime, if he’s close enough (which he should be for his turret form to do proper damage) this should get you to the medium range you need to primary fire him to death. Your team will hopefully assist too cuz everyone hates bastion (I main him. I know)
Dva also counters Bastion because her DM and high mobility allows her to live through the turret form, protect her teammates, and then Bastion won’t be able to get away.
Unfortunately, Zar counters Dva and Sigma cuz her primary fire goes through their DM/Suck.