North Nature Park in the Scenario Campaign Mode is the way to go for this achievement. There are pipes all along the entire stage in various boxes. There are also plenty of enemies to keep replaying the stage and get the achievement fast. Pick up with A to pick up and tap X to get a one-hit kill off of most of the enemies. Y is sometimes a better use in other stages but in this one, X is best. When you get to the end boss, there are at least two pipes in that area and enemies litter the area so have fun.