"That Negativitron's not going down without a fight!"
In the first phase, The Negativitron fires a beam at the player. You (in a HamsterTron 2000) will try the hit the Negativitron's brains five times. Right after the Negativitron fires a beam, move over to the brain. This will minimize your chances of being hit. Once you hit a brain on one side of the Negativitron, another brain will appear on the other side. Once you've done it five times, you will proceed to the 2nd stage. Note that there is an easier way with 2 players. Each player will get on each side on the Negativitron and smash his brains when the brain on their side pops up.
In this phase, you will have to hit the Negativitron's brains, this time 4 times. You will bounce on bounce pads and grapple on the bottom of them. This may look like the easiest part, but it is actually hard because you might try to grapple a bounce pad that is too far away and fall on the floor and vaporize (electrocute) to death. When you get all of the Negativitron's brains, you will proceed to the 3rd phase.
In this phase, Negativatron will try to shoot the player in a pattern. First, it will shoot tiny lasers at you. Then, he will shoot two tiny lasers at a time. Next, he will shoot medium sized lasers at you. After that, he will shoot two medium lasers at a time. Finally, he will shoot four large lasers at you. Then, the Negativatron will try to crush you (if he does, you will die). Then Larry Da Vinci or Victoria Von Bathysphere will pass a cake to you to throw at the Negativitron's brains. If you miss, you will get a second chance to hit the brain. But if you hit the brain, you will have to wait until the cycle finishes again. You will have to hit the brains 3 times. After the 3rd phase, the 4th and easiest phase will occur.
The (fourth and easiest) phase consists of a zero gravity type room, where you stomp on the Negativatron's final brain atop his pink negativity blob. In doing so, all creativity goes on a one trip tour back to Craftworld, the credits roll, and thus, you have beaten LittleBigPlanet 2!
- Eve is the only member of The Alliance that does not help you during the boss fight.