You'll most likely get this achievement first. All you need to do is win a match via pinfall.
To do this, you'll need to beat your opponent down to the red health bar and preferably empty it completely. After you've done this, press
to the side of your opponent's downed body and you will attempt a pin.
Hitting a signature or a finisher on a very low-health opponent, resulting in an empty health bar, will guarantee you the win as they won't be able to kick out.
Once you get the 3 count, and the win, you will unlock your 50G achievement.