This is how Starscream vs. Galvatron goes in Showdown.
[We see Starscream and Galvatron facing each other]
Starscream: Spare me your lectures! You know nothing of power!
Starscream: Do you know what real power is?
Galvatron: Get to the point.
Starscream: True power...is simple determination! Making the impossible possible through sheer FORCE OF WILL!
[Starscream releases a wave of force that makes Galvatron flinch and knocks the Autobots out of the sky]
Starscream: I have risked everything in pursuit of this power! I have given myself over to it, body and spark! Now witness...the power of one who has SACRIFICED EVERYTHING!
Galvatron: Ha! If you believe that... then you're a bigger fool than I thought! Witness the power of one who risks NOTHING!
Starscream: SO BE IT!
Galvatron: Enough magic tricks! Time for some hardware!
Starscream: You'll have to do better than that.
Galvatron: Bravo, Starscream. Your performance is so convincing, I almost want to applaud. [laughs]
Starscream: Oh, how generous of you. In turn, let me give you a big hand.
Starscream: You know it's pretty amazing when you think about it. With the power I already absorbed, I can increase the mass of my body at will. And soon I will multiply that power a hundred fold.
Starscream: Thus endeth the reign of Galvatron!
Galvatron: How can this be... am I... to be defeated... by Starscream?