Bonus Grid is the 20th Advanced and Expert floor in Monkey Ball and Super Monkey Ball. In Super Monkey Ball Deluxe, it is also the 20th Advanced stage, but also the 60th Ultimate stage with continues and the 80th without.
This stage consists of a flat square platform with borders around it and with bumpers and bananas placed diagonally to each other.
Perfect Score Tutorial
To get all the bananas, you simply have to roll diagonally, trying to avoid the bumpers. Touching a bumper will bump you back and forth in all kinds of directions, losing a lot of time in the process.