Bubble Jumps are a type of jump setup in kaizo where there are 2 enemies or items floating in bubbles with a tile or 2 of space between them. To perform the jump, Mario must jump into the top one, hold jump as he is colliding, then fall through, trigger the second bubble, then bounce off the enemy coming out of the top bubble. Bursting the bubbles allows Mario to fall through the air slower, allowing him to bounce of the enemy falling out of the top bubble. Bubble setups will differ a little, requiring you to hit the top bubble from different spots (i.e. from the side or from the top) and may require you to fast fall for a bit before regrabbing the jump button in order to make the jump work. Getting experience and a feel for bubble jumps is the only real way to know if input modifications are needed to make the jump successful. If you are falling below the enemy and failing to get a bounce, make sure you are holding jump through the entire process or make sure you are hitting the top bubble high enough.