Welcome to Gaia! ::

First form: Whatever color Prime is, that is the beam you have to attack it with. So Yellow=Power Beam. Purple=Wave Beam. White=Ice Beam. Red=Plasma Beam. The weapons you should use are Super Missile, Wavebuster, Charged Ice Beam, Charged Plasma Beam. Stay behind the pillars for as long as you can. They will be destroyed quickly, but every bit of cover helps. Most of its attacks aren't hard to dodge. But when it fires 2 blobs that slowly float towards you, destroy them. They can't be dodged, and they do a good amount of damage to you. When it fires a green beam, allow yourself to get hit with it. It won't do damage, but it will pull you towards Prime. This is a great oppurtunity to do some big damage to Prime. When it charges forward, go into one of the side grooves (you will get hit if you go in the middle one) in morphball form. After it passes, stand up, turn around, and continue attacking. After you deal enough damage to it, it will burrow to another place. Follow it. When you defeat it, it will burrow sideways rather than straight down. Then the real final battle begins.

Second, and final, form: This time, Prime has 2 attacks. It will lunge at you, which is sooooo easy to avoid, and it will slam the ground causing a shockwave to spreaqd out. Double jump over that. It will disappear regularly, but it can always be seen with one visor. Just remember to switch between Combat, Thermal, and X-Ray in that order as it disappears. The first time it disappears, switch to Thermal. When Prime disappears again, switch to X-ray. Then back to Combat, then Thermal, then X-ray etc. Eventually, it will form a pool of phazon and spawn 2 metroids. At first, regular metroids will come out. After you do some damage to Prime, 2 hunters will come out. When Prime is almost dead, 2 Fission will come out. You can defeat the regular and Hunters by freezing them with the Ice Beam, then firing a missile. But when against the Fission, use a Power Bomb. Once the Metroids are gone, jump in the phazon pool. Now you can fire the Phazon Beam, which is the only weapon the can hurt Prime. Fire until the pool dries up. Repeat the whole process until Prime is dead.