Watch Transformers: Robots in Disguise (2001- ) full episodes online.
Synopsis: When Earth is targeted by Megatron and his Predacons, Optimus Prime and his Autobots prepare for their coming by installing themselves in secret among human society, masquerading as everyday vehicles used by humankind with no knowledge of their true nature. When Megatron strikes and kidnaps famous scientist Kenneth Onishi, the Autobots ally with his son Koji to rescue him before Megatron can pry from his mind the truth of the ancient secret hidden somewhere on Earth.
After successfully re-energizing his ailing craft, the Megastar, Megatron rips the first clue from Doctor Onishi’s mind, and tracks the location of an ancient Cybertronian O-Part, only to lose it to the Autobots. Incensed by failure, Megatron recovers six Autobot protoforms from a crashed spaceship and brainwashes them into the Decepticons, led by the dark clone of Optimus Prime, Scourge. These new warriors prove much tougher opponents for the Autobots, who then have to deal with attacks from their own side when Optimus Prime’s embittered brother, Ultra Magnus, arrives on Earth to steal the Matrix from Prime. Realizing the Matrix can be shared between them, the brothers put aside their differences and gain the power to combine into Omega Prime, as well as using the Matrix’s power to give the Autobot Brothers new super-charged bodies.
Fearful of losing his position to Scourge, the bumbling Sky-Byte accidentally frees Doctor Onishi when he attempts to use the scientist to locate all the remaining missing O-Parts. Onishi is then able to help the Autobots gather all the O-Parts, which together form a map that points the way to Fortress Maximus, an ancient Cybertronian battle station hidden on Earth for untold ages and controlled by the will of human children. The awakening of Maximus in turn awakens Scourge’s ambition, and he leaves Megatron to perish in a collapsing temple so that he can take command for himself. Megatron, however, is transformed into the vampiric Galvatron and puts down Scourge’s rebellion before confronting Omega Prime in a final battle at the Earth’s core, where he is defeated by the Matrix Blade created by a fusion of Maximus’s energy and Magnus and Prime’s Matrix.