The quest is unlocked after completing the Testing... Testing... One, Two... quest.
"Perhaps due to lasting damage from being broken in battle, many of Terrako's memories are missing or corrupted. Get some things that might help your friend regain its memories."
"After hearing everyone recount stories of the past, Terrako's memory is just as clear as it used to be! The little Guardian seems excited to continue fighting alongside all of its friends."
- Terrako: Bonus Combo