Brobro is an NPC in Xenoblade Chronicles 2. He is a Nopon who is found near the Salvage Deck in the Argentum Trade Guild anytime after Chapter 3 has been completed after the 2.0.2 update, when he will give the party the Massive Melee Mythra Aux Core.
Brobro offers no quests or merc missions.
Brobro is likely named for the Smash Bros series, which his dialogue and the Aux Core he offers reference.