SpongeBob SquarePants: The Cosmic Shake

I found that the best spot to grind this was at the third checkpoint in Medieval Sulfur Fields: Garden Maze. If it is your first time entering this world, this checkpoint is right after you've finished sliding down the rainbow track. Once here, there are five Jellyfish surrounding the fountain area at the beginning of the maze. Press the X button when near each one to "catch" a jellyfish. When you've finished and caught all 5 in the area, you can reload the checkpoint and they will spawn back in. Repeat this process until you've caught 50 total and the achievement will be yours.

I found that the best spot to grind this was at the third checkpoint in Medieval Sulfur Fields: Garden Maze. If it is your first time entering this world, this checkpoint is right after you've finished sliding down the rainbow track. Once here, there are five Jellyfish surrounding the fountain area at the beginning of the maze. Press the X button when near each one to "catch" a jellyfish. When you've finished and caught all 5 in the area, you can reload the checkpoint and they will spawn back in. Repeat this process until you've caught 50 total and the achievement will be yours.

It may take about 10 mins but if you really want to get it spawn at Krusty krab go to the right karate chop one enemy to get to it faster catch it then pause go to check point and repeat.