Here is the full list of all 18 Elastrix achievements.
Solve a level without using any kind of band.
Hit a high score of 3000 or more in Trixball.
Get over 1000 points in Trixball in a single shot.
Beat level 23 of the Classic chapter without collecting any gems.
Shoot 200 Trix out of the cannon.
Beat level 8 of the Classic chapter without collecting any gems.
Finish the first chapter.
Get Perfect Shots in all levels of the first chapter.
Hit a high score of 1000 or more in Trixball.
Do a Trixball shot that only scores 10 points.
Have at least 10 Trix on the screen at the same time.
Keep a single Trix alive in a level for more than 60 seconds.
Get Perfect Shots in any 5 levels of the game.
Finish the Gravity chapter.
Get Perfect Shots in all levels of the Gravity chapter.
Beat level 7 of the Gravity chapter without collecting any gems.
Beat level 24 of the Gravity chapter without collecting any gems.
Hit a high score of 5000 or more in Trixball.