Megatron shows up as a literal tyrannosaurus rex and nobody pretends this is serious for a second. The animation swings hard on every frame, treating a dinosaur robot turf war like the only thing that matters. This is what happens when you stuff every version of Transformers into one timeline and let them go at it without apology.
In 2004, after the second season of the original Transformers, Convoy learns of a disturbance at the gates of Autobot City. The attacker is Beast Megatron, a tyrannosaurus who seizes command of the Destrons from Starscream. The original Megatron has been lost, and the Cybertrons are developing technology to tap solitarium, a newly found energy source. Warriors from both sides and from many eras arrive in this time through rifts called Blastizones, and they fight over that power. The two-episode special delivers mecha action with a time-crossing premise.