Online is pretty much dead for Rock Revolution so I recommend that you grab someone from either TA.com or x360a to help you boost for this achievement.
Once you've got someone you have to beat them in 10 ranked matches. Remember: RANKED. After the score screen at the end of each song you'll get kicked back to the menu, so you'll have to host a new match for each song. Song choice, instrument choice, and difficulty do not matter. The person who is losing on purpose doesn't have to bother playing at all and the person who is supposed to get the wins only has to hit one note so they their score is higher than the other person. You can, of course, just play normally with each other and once the better one out of the two of you gets all the achievements the normal way you can start giving the rest of the wins to the less skilled player for free.
Achievements I recommend you work on simultaneously: