D.Va's ultimate Self Destruct will do damage to her if she's within line of sight of her mech, so by hiding behind cover, D.Va can avoid being killed by her own ultimate.
Is it possible for D.Va to use her own teammates as cover to protect herself from her own ultimate? So, for example, could a D.Va player hide behind a friendly Roadhog to avoid taking from her own ultimate?
Best Answer
Long overdue update to this answer: D.Va can no longer self-damage with her ult, so this question/answer is moot.
Previous answer:
D.Va can't use allied hitboxes or allied barriers to block self-damage from her ultimate. She can, however, use an enemy barrier (Winston's or Reinhardt's, but not Zarya's as it is targeted) to block self-damage.