This is how Starscream defeats Galvatron goes in Showdown.
[Galvatron gets up]
Starscream: So, the worm still squrms.
Starscream: Why don't you give it up. You are only prolonging your pain.
Galvatron: I never rest if I lost to a weakling like you!
Starscream: Bold words. Maybe I put them on your tombstone.
Galvatron: You wanted to risk everything?! So be it!
Starscream: I won't hold anything back!
[Starscream and Galvatron start charging up their energy]
Soundwave: What are they doing?
Sideways: Those two are channeling enough energy to wipe out small planets!
Soundwave: Well, I'm not sticking around to hear that groove. Let's warp our tails out of here.
Sideways: We can't leave without the Omega Lock! If we do then we failed our planet. Our people!
Soundwave: Let's do it.
[Soundwave and Sideways teleport away. Starscream and Galvatron start fighting]
Jetfire: That's impossible! No one can channel that much energy.
Optimus Prime: If either one of them survives the battle, we'll have to fight them for the Omega Lock. But I don't know if we have a chance against that kind of power.
[Soundwave and Sideways arrive at the Omega Lock's location]
Soundwave: I think I see it.
Sideways: I'll get it. Save yourself!
Soundwave: No way, brother. We're in this together.
Galvatron: Farewell, Starscream!
Starscream: Galvatron, say hello to oblivion!
[Galvatron and Starscream crash into each other]
[An explosion happens]
Trixie Lulamoon: Galvatron? Obliterated?
[Starscream is seen floating above the smoked crater and looks down at it]
Starscream: You see, Galvatron, when don't you risk anying in the pursuit of power, you could wind up with nothing. That's why I risk everything.
Starlight Glimmer: I can't believe he defeated him.
[Soundwave and Sideways appear with the Omega Lock and give it to Starscream and he takes it and turns to Thunderblast, Thundercracker, Ransack, and Dark Crumplezone]
Starscream: Follow me, warriors.
Soundwave: Galvatron has been defeated. Starscream is the new Decepticon leader.
Sideways: All hail Starscream!
[Thunderblast, Thundercracker, Ransack, and Dark Crumplezone look at each other before bowing to Starscream]
Thunderblast, Thundercracker, Ransack, and Dark Crumplezone: (together) Long live Starscream.
[Starscream, Soundwave, Sideways, Thunderblast, Thundercracker, Ransack, and Dark Crumplezone leave Gigantion]
Thomas: What happened to Galvatron?
Vector Prime: I say he was blasted into another dimension.
[High above the planet, floating on the solar winds... Galvatron's cannon drifts in the cosmic night]