Optimus Prime's Big Damn Heroes moment in the animated movie, beginning with "Megatron must be stopped, no matter the cost," and climaxing with "One shall stand, one shall fall." So good that both were voted to be inserted into the live-action version, and the song playing during the scene ("You got the Touch...") has become legend.
Runs down two Deceptions, and without pausing he shoots down another six or seven more in mid-air. Then comes the final battle with Megatron, and Optimus whips him in unarmed combat. After Hot Rod causes the fight to turn, a stabbed and shot Optimus still knocks Megatron over a three story fall with the Polish Hammer.
Special mention goes to the part when Megatron jumps into the air, the sun backlighting him for added awesome, and dives toward Prime....only for Prime to uppercut him in the face. How the HELL did Micheal Bay not swipe this shot for his movies?
Slag (not to be confused with the triceratops dinobot) in one shot — DEFINITELY one of Galvatron's better moments
And the one liner afterward.
Galvatron: Will anyone else attempt to fill his shoes?
You're forgetting the exchange Starscream and a dying Megatron had before this.
Megatron: Wait! I still function!
Starscream: Wanna bet?
What makes the payback mentioned above even more priceless.
If you're going to talk about the animated movie, let's bring in Megatron and Soundwave. After the battle with Optimus Prime, Megatron is near death and what does Starscream do? He kicks him when he's down and turns to leave without him. Megatron can only grab Soundwave's leg and say "Don't leave me." Soundwave responds, "As you command." and promptly carries him. This scene is awesome enough to rival Optimus Prime's death scene and further proves why Soundwave is a very popular character.
It's also a character-defining moment for Starscream — namely, his biggest Kick the Dog moment of the entire series so far.
Keep in mind, Starscream kicks Megatron with all his might.. with the same foot he had earlier blasted apart to escape being crushed.
Another Dinobot moment: Slag single-handedly defeated Devastator, after all autobots failed (including his fellows Dinobots).
Unicron's minute-long transformation. While Unicron's nature is well-known to us now, it certainly wasn't in 1986, and seeing him transform from a planet into a planet-sized robot on the big screen is an experience you won't forget.
He also shuts Megatron up before he can object to his summoning, showing how in control he is.
Grimlock leading the Dinobots to attack Unicron from behind, and giving the planet eater a literal ass-kicking. Also managing to do more damage than anyone other than Hot Rod/Rodimus to Unicron in the process!
His comment as he starts to do so is awesome in itself.
Grimlock: (as he transforms) Me Grimlock kick butt!
THE ENTIRE. FRIGGIN. SOUNDTRACK. Particularly Unicron's Theme; you hear that theme and you know something bad's about to happen.
Say what you will about the plot, the cheesiness, and any other flaws it might have. But the soundtrack elevates this movie.
Kup solidified his standing as a badass character right from the start. During the assault on Autobot City, Kup leaps onto Blitzwitz's cannon while he is in tank mode, not only managing to divert the canon away from firing at Hot Rod and Daniel but also blast Shrapnel out of the air who then crashes into Blitzwing. Kup takes out two Decepticons at once, without ever drawing his weapon or firing a shot.
How has Hot Rod not gotten more love on this page? Between basically opening fire on Megatron and the Decepticons when they first attack Autobot City, and his awesome underwater battle to save Kup, the movie went a long way to make you both forgive him for his part in Optimus's death and accept him as the new Prime.