Becoming an Independent Being
In Mario's Adventure 3, the T-5001 was defeated in its final form, leaving nothing but its brain. It turned out to be surprisingly small: about the size of a watermelon. Then, for the safety of the planet, the T-5001's Earth-body was restored, leaving the brain lying somewhere on its surface. There, it was found by C2, who had just gotten out of the hospital after being severely injured months before, during the events of The Ultimate Showdown of Ultimate Destiny. He took the brain back to the doctor who had healed him, Dr. Batman, and asked him about it out of curiosity. Dr. Batman took a look at it and claimed that it once belonged to an extremely powerful being, which made C2 think of a plan to finally become as powerful as his double, Chuck Norris. He asked Dr. Batman to transplant the brain of the T-5001 into his own head. Dr. Batman complied, inadvertently causing the brain to possess C2's body. After a long and grueling fight, Dr. Batman finally stopped C2 with help from a slew of cartoon characters and the Chaos Emeralds. Then, the brain of the T-5001 shape-shifted into Mother Brain, but it was stopped once more. Finally, once the brain blew up, all that was left was the brain stem. Dr. Batman took this brain stem to the hospital and sealed it in a triple-reinforced, water-filled, Plexiglas chamber. There, the brain stem managed to come to life once more through sheer force of will and absorb the water around it, turning into Chaos. Then, Chaos escaped to wreak havoc and collect the Chaos Emeralds, only to be stopped by Dr. Batman once more. After this, it was defeated by the T-2500.5 and forced to change forms again and again, until it reached its planetary Final Form. The T-2500.5 used the Chaos Emeralds and Super Emeralds to power up, gaining enough power to fight this form to a standstill and reduce it to a mere planetoid. Knowing that this form could not be fully defeated, the T-2500.5 sent it back in time, where it grew into what we now know as the UnWorld.
The T-5001's brain (in its default form) is a metallic silver color and has an iridiscent blue aura around it. When it was first discovered, after being separated from the T-5001 in its final form, it was about the size of a watermelon. However, when it became Mother Brain, it turned an brownish-orange color and lost its blue glow. It also grew teeth, spikes, and a single eye. After being defeated in this form, it became nothing but a pale, pinkish-purple brain stem, which is all that is currently left of it.
- Mother Brain: Just a brain on top of an immense, dinosaur-like body. Appears in various shames in the Metroid series.
- Chaos: A humanoid creature made of water and a brain floating in its liquid skull. Has the ability to turn into a puddle, extend its liquid arms, and become bigger and more powerful with each Chaos Emerald it collects. It can only transform into this form if it is surrounded by water. Otherwise, it just becomes Tomars.
- Tomars: A white, humanoid creature with a gold head with red eyes and a mouth that does not move when he talks. Has the ability to create a giant shockwave and travel through computers.
- Tomars-X: An upgraded form of Tomars. It wears a blue suit and a golden helmet with an X on it. This form was not achieved naturally, but was created when Tomars used Susan and Mary Test's mutation ray to gain superpowers. He became so strong that he even killed Turbo Hyper Mordecai, a form that Mordecai achieved with the Chaos Emeralds and Master Emerald.
- Froslass: A weird, ghost-like creature that is coloured white and purple. Has the power to send a breath of ice at its opponent. It can only change into this form if it is surrounded by ice or snow. Otherwise it just becomes Pizarro.
- Pizarro: A weird, clown-like doppelganger of Pooper Man. Has all the powers of Tomars-X, but stronger. Also, it cannot create shockwaves and travel through computers like Tomars-X could.
- Pozars: A combination of Pizarro and Tomars. Has all their powers, but even stronger and even harder to kill. Unlike the other two forms, it is immune to its own attacks.
- Final Form: A robotic copy of the planet itself...but with limbs and a head! This form was sent back in time to become the Earth itself.
- Shapeshifting (only in life-threatening situations)
- Telepathy (only used for communication)
- Possessing others
- Copying the appearance of others
Abilities in Other Forms
As Mother Brain
- Rainbow laser
- Stomping on people
- Attacking with extendable arms
- Turning into a puddle
- Growing more and more powerful with each Chaos Emerald it collects. Increases in its physical power range from growing some bones in its arm to becoming a Godzilla-like monster.
- Creating shockwaves
- Traveling in and out of computers (or any kind of machinery, for that matter)
- All powers mentioned above
- Laser eyes
- Ice breath
- Laser beams
- Throws snowballs
- Can turn into ice
- All combined powers of Tomars-X and Pizarro (minus the shockwave and traveling through machinery)
In Final Form
- Unknown (potentially apocalyptic)
List of People It Has Possessed
Main Article: T-5001's Neuron
After the T-5001's brain was "defeated" by the T-2500.5, all that remained of it was a single neuron (not counting the rest of the brain, which had turned into the UnWorld itself). This neuron acted as a sentient being of its own, intending to finish what the original T-5001 had started.