Here is the full list of all 21 Game-Kun: Input Challenge achievements.
Get a streak of 10!
Get a streak of 25!
Get a streak of 50!
Get The A-RT Input Correct
Get The A-LT Input Correct
Get The Y-A-Y Input Correct
Get The B-A-RT Input Correct
Get The B-A-RB Input Correct
Get The B-B-Y Input Correct
Get The B-A-Y Input Correct
Get The A-A-A Input Correct
Get The B-A-A Input Correct
Get The B-LT Input Correct
Die 11 Times!
Die 99 Times!
Get 1000 Inputs Correct
Get 10000 Inputs Correct
Get a streak of 100!
Get a streak of 200!
Get a streak of 300!
Get a streak of 500!