For this achievement you'll need to win a round without taking any damage in Arcade Mode.
For this to be an easy task after choosing Arcade Mode select the following settings:
Round Count: 2
Time Limit: 30
Attack Power: +3
Number of Barriers: 1
Once the match starts just DESTROY then with relentless attacks and never letting up. And soon after you'll win the match and earn this 60G achievement!
The following video will depict this solution!