For the main attraction of grappling, you must perform a variety of Cerebella's throw moves 100 times. The basic fundamental grab in the game can be done by pressing + . Remember, you must be a certain distance to your opponent in order to connect with these throws. Below are some of her other grab moves:
Diamond Drop: + +
Merry Go-Rilla: + +
Ultimate Showstopper: 360 Motion + +
Simply start up a 2 Player Local Versus match and use each one multiple times until the achievement pops. You can simply spam + if you want or any other throw move 100 times and it will still unlock. This should also be attainable in Sparring Mode while performing her Ultimate Showstopper Blockbuster grab move repeatedly as the video shows.