If you could steal one character's signature move...

[SixWingedAsura]

Serpents Infernal Rapture!!!

Come on, an invulnerable kick that sends your opponents sky high, is extremely fast and can (as long as you're in unlimited form) deal stupid amounts of damage? Sign me up!

 

[Deku-Miguel]

a few words: PK STAR-STORM!!!

 

[The Shade]

Tony Jaa's "Flying knee-kick to the chest," which be begins every fight with.

HooPAH!!

Whaddya mean, "Tony Jaa is a real person"? As if anybody could actually do any of those things.

Commander Shepard's Warp. Who doesn't want to make to be able to tear something apart at the atomic level?

I'm Commander Shepard, and this is my favourite answer on the Citadel.

 

[Soushi]

I, Soushi Vi Farfenrier herby command you, all of you... Will become my slaves!!!
Oh yeah, Geass for the win.

In a close second would be the force from any jedi in Star Wars, that's kind of a signature move.

Then of course there is the death note...

 

[lex.nero]

Kurosaki Ichigo's Final Getsuga Tenshou from the bleach manga. If you don't read Bleach, then shame on you.