Select the event Coastal Cruise in the Sunshine Coast Tour in World Tour, you can play as any character. Play on easy to make this easier. When in the race, grab the first item box you come across and whatever power up you get that causes damage to another racer make sure it hits. Then win the race without using any damaging weapons, boosts and gloves are okay. The achievement will unlock at the end of the race.
Note: This does not work with Drone and the Blowfish (fired forwards)