I played a match where my Braviary, which has defiant, used defog on a Corviknight, that had mirror armor, and it bounced the evasiveness drop on to Braviary which triggered defiant; boosting Braviary's attack. So I'm wondering if this would work in doubles, kinda like beat up+justified did. You would use defog, or snarl, or some weak damaging move that would lower a non-important stat that would be bounced on to the defiant (or other ability that would be affected by stats being lowered) boosting your other stats.