SpongeBob SquarePants: The Cosmic Shake

You use your bubble stun move with the RB. You'll see an icon above enemy's head that look like a bubble wand and a bubble. If you see this icon, you'll be able to push RB to blow a bubble at them and it'll most likely home in on the enemy, and place them in a bubble that will stun them for a time. If the enemy is too close you may miss, so you'll want to at least be a medium distance away for the homing to work. Simply do this 100 times throughout the game and this will pop.