Here is the full list of all 33 Super Multitasking achievements.
Standard Mode: Play 2 simultaneous minigames (Maximum difficulty excluded)
Standard Mode: Play 3 simultaneous minigames (Maximum difficulty excluded)
Standard Mode: Play 4 simultaneous minigames (Maximum difficulty excluded)
Standard Mode: Last for 10 seconds or more on Maximum difficulty
Standard Mode: Last for 3 minutes or more
Standard Mode: Beat the default #1 scores on Easy, Normal, Hard, and Maximum local leaderboards
Standard Mode: Beat a personal best by 1 second or less
Standard Mode: Came within 1 second of a personal best, then failed
Standard Mode: Play all unique minigames at least once
Standard Mode: Fail all unique minigames at least once
Challenge Mode: Fail any Challenge 5 times in a row
Challenge Mode: Clear "Just Follow Directions," ending both minigames with 0.1 seconds or less remaining
Challenge Mode: Clear "Now You See, Now You Saw" with all seesaws ending almost completely straight
Challenge Mode: Clear "Hurry Up!" firing *just* enough shots to beat the boss
Challenge Mode: Clear all Challenges
Challenge Mode: Clear all Challenges using keyboard controls
Challenge Mode: Clear all Challenges using 777 total attempts or fewer
Challenge Mode: Clear Challenges 1-15 in order, in one session, without failing any of them
Practice Mode: Set up any situation and last for 2 minutes or more (Game Over On, AutoPlay Off)
Practice Mode: Try any situation with Minigame Difficulty set to 100% (AutoPlay off)
Practice Mode: Complete any situation with minigames in every slot (Game Over On, AutoPlay off)
You quit Speedrun Challenge Mode. But you did try!
Challenge Mode: Failed "Opposite Day" 5 times
Challenge Mode: Failed "Number One"
Failed "Flappy" by hitting the ceiling
Failed "Shooting Range (Top)" by running out of ammo
Failed "Paddle" without ever touching the ball
Failed "Space (Top)" or "Space (Bottom/Attack)" without defeating a single alien
Failed "Greater" by running out of time
Failed "Fruit" by physically pushing a fruit offscreen
Cleared "Space Boss" just before the boss hit you
Bonus Mode (Inquisition): After lasting for 2 minutes or more, failed by answering a question incorrectly
Earned all Achievements!