Pure

People have suggested that the achievement will not unlock during freestyle, and it will also not unlock if the other player(s) quit out of the match. It would be easiest to boost this achievement at the same time as using a Class D engine to beat a Class A engine. The online community isn't dead, but it isn't vibrant either, so boosting a game shouldn't be too difficult. If you want to try to beat someone else legitimiately, good luck, as anyone still dedicated enough to be on the servers are usually pretty good at the game.

i just tried this and thought i would add that it doesnt seem to pop (or at least didnt for me) if the other rider quits before the race ends. probably best to boost than do it legit as lots of people quit out.