Here is the full list of all 27 Super Slime Arena achievements.
Punch every slime as punch slime in a single match
KO 5 slimes with one beam as beam slime on celestial clock
Get a KO as stone slime after dropping all the way from the top of the screen
KO an opponent on the top branch of Rainbow Jungle while you stand on the ground
Get a simultaneous KO with two kick slimes
Get a simultaneous KO with two teleport slimes
As teleport slime KO a rainbow slime by teleporting inside the rainbow
KO three slimes in one beetle slime charge attack
KO three slimes in one tornado slime spin attack
Have 10 summoned jars out simultaneously
Play a 4+ player local multiplayer game
Play a 8+ player local multiplayer game
Play a 12+ player local multiplayer game
Play a 16+ player local multiplayer game
Play a 32+ player local multiplayer game
Play using an unusual controller
Play a match with a controller binding that only uses buttons
Transcend the bounds of the stage
Complete an online match
Win every round in a 32+ round Monobattle
Win a match without dying once
Don’t press start. For 16 minutes.
As dash slime dash through wave slime’s wave and get a KO
Pause and quit a match right before you lose
On Countryside Station get a cumulative 5,000 KO’s as stone slime
Get 777 on the Lucky Neko slots
Catch a ride on Leia the salmon