Here is the full list of all 42 Knack trophies - there are 28 bronze, 9 silver, 4 gold and 1 platinum.
Collected the clear crystals in Chapter 4-2 without being detected by the security robots
Unlocked an upgraded Knack
Achieved 50 consecutive hits with the Combo Meter equipped
Defeated the Chapter 13-5 boss
Defeated 20 enemies as Stealth Knack and completed the chapter
Defeated the Chapter 11-5 boss
Defeated 8 or more enemies with a single Super Move
Achieved 20 consecutive hits with the Combo Meter equipped
Constructed a Gadget
Destroyed the 3 anti-aircraft guns in Chapter 8-2 within 5 minutes
Defeated the Chapter 7-5 boss
Defeated 5 gunships by throwing cars
Defeated the Chapter 3-5 boss
Acquired a Crystal Relic
Defeated 100 goblins
Completed a non-boss chapter without using any Super Moves
Defeated 100 robots
Acquired a Gadget part
Discovered a treasure chest
Received all trophies
Landed 100 hits using the Dash Attack
Acquired a total of over 100,000 relics
Defeated the three Gatekeeper Goblins and cleared Chapter 3-2 without dying
Cleared a chapter as Vampire Knack
Defeated the Chieftain's Mech using Brittle Knack
Defeated Gundahar's Robot using Massive Knack
Defeated Katrina's Mech using Sunstone Knack
Defeated the Giant Orb using Dark Knack
Defeated all bosses using Diamond Knack
Discovered all of the treasure chests
Acquired all of the Gadgets
Unlocked all upgraded Knack characters
Completed a chapter only using Super Moves on enemies and without dying once
Completed all chapters on Normal difficulty or higher
Completed all chapters on Hard difficulty or higher
Completed all chapters on Very Hard difficulty
Completed a Time Attack stage
Achieved five-star ranks in all Time Attack stages
Completed a Coliseum Attack stage
Achieved five-star ranks in all Coliseum Attack stages
Defeated a boss without taking damage
Completed a stage without taking any damage on Hard difficulty or above