Defeating The Boost Guardian:

In this battle, your energy will slowly decrease because of the Dark atmosphere. There are no Light Crystals to help you. There are four pillars in the room, and each contains the Ultra Energy Unit when broken down. They are essential to your survival. The Boss will take two forms, normal and liquid. When in its normal form, blast it down with a Super Missile, as it will damage him the most. The Boss will then form into a morph ball and start spiking through the room randomly. Jump over it, or form into a ball to get out of its way. Also watch out for its minions. After three to four spikes, it will follow you on the ground in maroon liquid form. Quickly form into a ball, roll around, and drop bombs behind you. It will repeat spiking and forming into liquid again. Repeat this and it will finally revert back to normal form. Blast it with the
Super Missile and repeat the entire process until it is dead. Once it is defeated, the Boost Ball upgrade is yours.

Before you enter the hole to the Boss' chamber, switch to the Light Beam. By doing this, you will start with it when you are out of morph ball mode. When the battle begins, you will automatically change out of morph ball mode. Either scan him or begin charging your Light Beam (which will be your default) and try to get two or three shots on him before he starts glowing. When he glows red, he is temporarily invincible. When he is in ball form, switch to morph ball mode. This will make avoiding his minion Ing easier. If you can, drop a morph ball bomb in front of him before he charges off -- look for the line down the middle of his ball form. He will charge in one of those two directions. If the blast hits him while he is in ball form, he will instantly turn into his liquid form, in which case he will follow you around. Drop M.B.B.s to damage him. If he starts boosting around before you hit him, roll around, dropping morph ball bombs and try to avoid him. If he hits the bomb blasts while he is moving, he will stop and turn into his liquid form. After about three bombs in his liquid form, he will change back to his solid form. Change back to your gun mode and repeat those steps. He should die after about three repetitions.