You will need to block an opponent’s shot six times with one character for this achievement; I highly recommend using the tall character you created. To make this achievement easier, move your block slider to 100, and move down the opponent’s shooting sliders.
If you have a second controller, there is a method hat you can sue to make this easier to get. When your second controller has the ball, put your tall character in front of the character with the ball. Press on the second controller to have that character shoot the ball, and then quickly press and hold and on your primary controller to block. This may take a few tries to get the timing down, but it should block your opponent’s shot. Repeat this process 5 more times for the achievement.