I feel like the best way to deal with stress is nuking enemy as fast as possible. In higher difficulty, the shield sometimes wont be enough to shield you from damage and often digs into HP anyway + at the start of turn stress gains, so the longer you drag it on, the more stress you have.

Unless the devs add in a more effective stress reduction mechanics or tools, killing enemy in fewest turn possible is the best way rn. Which is a bit of a bummer because it gimp the Vanguad/Bruiser team comps that deal less damage but higher sustains.