This can be done in a private lobby with a friend, to do this simply go to
Battle Mode from the main menu, selecting
Online then
Lobby, followed by
Create Lobby, from here
do not push create lobby just yet, instead be sure to put
Lobby Size to 2 and
Friend Invite Slots to 1, you can now press
Create Lobby. invite your friend and simply approach your friend and press
right beside your opponent/friend. Do this for as many matches as you like but you should be able to do so in 2matches/4rounds, either way, you'll obtain your achievement.
Note: some people may unlock the achievement at 50 exactly while others will have to wait until the match is fully finished, which happened to be the case for me.
For those who are unable to do this because they have no friends/or friends that play the game, or no-gold or whatever the situation maybe, you'll have to do this the real way in
Arcade Mode but here are a few tips to help you out if you are struggling.
For starters you can use the
Space Infinity Stone/The Blue Infinity Stone which will draw your enemy towards you which you can then follow up with
for the grab move.
Another thing that can be helpful for both methods is using the Character
Firebrand (the small red dragon on the Capcom side) his grab reach is slightly further than most characters.
Hopefully this helps good luck.