Accolades are tasks given by the game, and, while it doesn't are needed to a 100% file, some players like to have then, as some of then give XP boosts.

Accolade	How to unlock
Ambassador	Have 1 Skylander of each element.
Captain	Have 1 non-Starter Pack Skylander (3DS starters can be used, but starter variants not).
Chief Scholar	Collect all Story Scrolls (including Adventure Packs).
Commander	Have 12 different Skylanders.
Elite Agent	Make 1 Skylander complete all 32 Heroic Challenges.
Fashion Elite	Collect 10 Hats.
Field Marshal	Have 24 different Skylanders.
General	Have 16 different Skylanders.
Grand Admiral	Earn all Accolades.
Master of Skyland	Have all 32 Skylanders.
Power Excavator	Collect the Soul Gems of the 3 Starter Pack Skylanders.
Savior of Skylands	Complete Story Mode (not including Adventure Packs).
Seeker Adept	Collect 10 Legendary Treasures.
Sergeant Warrior	Have 8 different Skylanders.
Skylander Superstar	Earn 3-Star Rank on all Story Mode chapters (not including Adventure Packs).
Soul Warden	Collect all Soul Gems.
Student of Thought	Collect 10 Story Scrolls.
Treasure Hunter	Collect all Legendary treasures (including Adventure Packs).
Wardrobe Saint	Collect all Hats.