Glitches in Kirby: Squeak Squad
In any 45-degree slope ledge that Kirby can go up through from below, by standing on the very edge, Kirby will start flickering between falling and landing. This happens because the game cannot tell if Kirby is under the ledge or on the ledge. This glitch is easier if using Metal Kirby since the position is pixel-perfect. 
Wall Clip glitch
In any stages that have 45-degree slopes with tops end with a wall and Sword Knight, use Ghost Kirby to possess Sword Knight, then position him next to the wall 1 or 2 blocks away, and use the sword lunge into the wall. Kirby may clip into the wall, but it may take a few tries to do so.