I've read all of the above achievements thoroughly, and they (surprisingly) don't seem to cover in exact detail the most efficient way to boost this achievement.
Here are the steps I took, and what I believe to be the most efficient way to go about getting this:
1. Get your buddy in chat, and create a ranked, 7 song battle mode match. Select any difficulty other than easy. Have your partner search for these specific game criteria and join your lobby. Almost nobody plays 7 song ranked battle matches, so this isn't difficult. Your partner will still occasionally wind up in a strange lobby, but more often than that, someone random will join yours. This is annoying, but simply create another one, or wait for them to leave.
2. Fill the song queue with Slow Ride.
3. Player One strums immediately and fails out three times, then Player Two fails out four. Switch; Player Two fails out three times, Player One fails out four. Since every song played counts as a 'ranked match played' for the achievement, you will maximize your game-win time and minimize your time creating lobbies, which admittedly is the most time consuming part of this achievement. Two matches will therefore net each player 7 out of 500 wins toward the achievement.
4. Rinse and repeat for about 7 hours. It should be noted that the MOST efficient way to obtain this is for both players to be working for it. It would take one player approximately 6 hours to get it, but only 7 or 8 for both; this is because you will be maximizing 'game-win time', and not simply creating lobbies for one person to get four wins and repeating that.
1. You can be in a private chat or a party to acquire this; both have been confirmed.
2. No notes need to be hit by the other player. It counts as a win, not a tie, even if both players are at zero percent.
3. The guitar hero scoring web site is unreliable at best where this achievement is concerned. During my boost for this, the site only recorded 20 battle wins for me, overall, when I should have had around 400.
4. This method can be used to obtain the 15 consecutive standard controller wins, "The Long Road Ahead" (will pop after 100 wins), and :Search and Destroy.
5. Progress for this achievement is stored locally. What I mean by this is, if you win 400 ranked songs on one storage device, and if that storage device fails and you have to create a new save (as I did), you will have to start from zero. What the GH website says does NOT count if you haven't done all 500 of these on one storage device. I had 425 legitimate Pro Face-Off wins when this happened. Feel my atomic rage.
6. I wanted to note that this achievement popped for both myself and my partner at almost exactly 500 wins. This may not be the case for everyone, as I see people logging up to 700 wins (or even less than 500) before this achievement popped, but then again I see lots of references to the win tracking on the GH site, which my experience shows to be completely unreliable. At least to us, it appears that the in-game win tracking has an accurate counter.
Special thanks to Zacry072 for boosting this with me.
I will be updating this solution with pertinent information if it is brought up. Happy boosting!