Boost On is a command that engages the elbow-mounted jet boosters of Mechamaru, allowing for a boost in speed and momentum. It can be used to activate the boosters in either of Mechamaru's arms or both at the same time.
Boost On is mainly used in conjunction with other commands in order to increase Mechamaru's attack power. When used alongside Sword Option, the Ultra Spin attack is extremely fast and powerful. Enough so to obliterate a tree with a single strike.
Boost On can also be used to increase Mechamaru's maneuverability whenever it requires a quick boost in speed. Using both boosters at once give Mechamaru enough speed to instantly propel himself behind his opponent, blitzing past their guard completely.