Here is the full list of all 8 Slime Slam achievements.
Complete a rank 1 challenge.
Complete a rank 3 challenge.
Complete a rank 5 challenge.
Gain 50,000 points in Endless Mode.
Reach level 10 in Arcade Mode.
Reach level 20 in Arcade Mode.
Gain 20,000 points in Endless Mode, with periodic garbage turned on.
Gain 20,000 points in Endless Mode, with 5 layers of Hard garbage.