Here is the full list of all 44 Generator Rex: Agent of Providence achievements worth 1,000 gamerscore.
Collected All The Samples For Doctor Holiday
Successfully Wiggled Free Of 20 Spider Webs Without Taking Damage
Defeated 100 Enemies With The Punk Busters
Knocked 20 EVOs Out Of The World
Beat All Agent Six Time Challenges
Beat Quarry In 2.5 Mins. Or Less
Indirectly Defeated 30 EVOs
Beat Any One Agent Six Time Challenge In Under 10 Mins.
Beat One Agent Six Time Challenge Level
Killed All EVOs And Take No Damage In Rex Ride
All Upgrades Purchased
Finished The Campaign
Defeated Giant Van Kleiss
Defeated Van Kleiss In Abysus Castle Without Taking Any Damage
Collected All Items Of Rex's Past
Defeated 100 Enemies With The Slam Cannon
Defeated Breach
Defeated 100 Enemies With Omega Builds
Opened 30 Supply Boxes
Defeated 100 Enemies With The Smack Hands
Cured Aquania
Acquired The Blast Caster
Defeated Biowulf
Defeated Van Kleiss In Providence
Collected All The Samples Of Any 2 EVOs
Saved Doctor Holiday
Acquired The Bad Axes
Recovered The Funchucks in Hong Kong
Completed The Rex Ride Sequence
Encountered Circe
Collected All The Nanites And Did Not Get Hurt In Sky Diving
Defeated The EVO Death Bunny
Gathered All Computer Info From Dr. Rylander's Lab
Solved The Puzzle In The Temple
Got A 60 Hit Combo
Defeated 200 Enemies
Defeated 100 Enemies With The BFS
Collected The 1st Sample For Doctor Holiday
First Upgrade Purchased
Defeated The Multi-Head EVO
Got The First Item Of Rex's Past
Completed The Tutorial In Mexico
Got A 20 Hit Combo
Successfully Flew Through The Circular Debris While Sky Diving