This achievement is straight forward. I can CONFIRM that you DO NOT have to get a black belt on all the challenge to complete this. As long as you go through the motion it doesnt matter what belt you get(even white) it will count as being completed. NOTE: You have to get better than a white belt on the 10th challenge of each challenge type for it to count as completed challenge.
The hardest challenge that involves a lot of luck is the advanced stand-ups 10th challenge. Other than that this achievement is pretty simple