On the field there will be
11 opponents that you need to hit with a power-up, the easiest way to do this is a long race with only bubble power ups.
First go to 'Play - Go!' and press
to make it a custom event and change the laps to 9laps, and change power ups to 'Bubbles Only' then begin a race on Belgium - 1000cc.
Take your time on the track and work your way from the back, when you hit an opponent with a power up a badge will appear on the left of the screen with that drivers name, pause the race and note down the name and move onto the next driver.
The trophy will pop mid race.
Note if you get this well before the end of the 9laps (Took me 3) you can use this time to try and unlock