Turn 5 is already incredibly easy. Only an overall terrible team can have problems with it.

You can have one bad tank and it wouldn't matter as long as the other one is decent. The bad one can take a dirtnap.

DPS has a shocking amount of leeway to be less than ideal, with echo and the ubiquity of i110 weapons.

Echo and gear makes healing easy too.

...But asking to fix bad randoms is like asking to cure stupidity on the internet.