For this achievement simply wait until the enemy uses his Special Attack then lift your arms up to 'block'. If you have more than one option when the enemy uses his Special Attack, it's the middle option. One strategy that may work is this: Go to Score Attack > Saiyan Saga > Raditz. Set the difficulty to easy. Once in the fight, charge your Ki Meter until the box above the Ki Meter appears, it will show a character jumping, follow suit and jump when this appears. You will enter an Assault Gauge quick-time event, you can pass or fail this if you want but either way you will now be far away from Raditz. He seems more likely to use his Special Attack under these conditions, so basically just keep waiting until he launches an attack. You can turn on the Eternal Youth QR code if you like to avoid dying.