I got this one without even trying. It shouldn't be too difficult, especially if you know one character really well and can land their DM's and SDM's regularly.
You should be able to get this one while going for The King of Fighters achievement. If you don't have enough points, you'll just have to keep playing the Single Player mode until you are able to net enough. Again, I highly suggest Kyo; even button mashing with him lands in DM's and SDM's quite often.
Note: To make these easier, make sure that you do the following in the Options menu:
Set the difficulty to 1 (Easiest)
Set your players power gauge to MAX
Set your defence to level 8
Set CPU's defence to level 1