It should ideally be something that can be hit on anyone, anywhere, anytime. Anyone can take a Rock Bottom, Stone Cold Stunner, or Pedigree. But can you picture Cena giving an Osaka Street Cutter to a guy like Rikishi, Mark Henry, or Albert? Bautista, sure. But not Cena.
However, I'd be very happy if his finisher doesn't just end up as a Big Boot, a Choke Slam, or a Superkick. Those are probably the three most overused finishers in wrestling today.
Heard the name a bit earlier in the thread, and I'd just like a description: What is a Proto-Plex (I don't get OVW here in my neck 'o the woods).
Also, here's a pretty cool finisher I wouldn't mind seeing Cena use. The Shining Wizard, or for those who have Smackdown 3, Flash Magic (basically a stiff-ass knee-of-doom to the head). It can be hit from any position and used offensively or defensively. Then again, if WWE's not too keen on using head-dropping maneuvers, they probably wouldn't feel to great about a guy using a running knee to the temple... But I'd still mark out if I saw anyone using it.
"All born equal unless you're Canadian Then halfway through decay like Uranium You define what's death-defying Get the most out of life or at the least die trying Are you Evil Knievel jumping a train? Or running with scissors like Frasier Crane? Have really good times doing really bad things ‘Cause the show ain't over ‘til the fat lady sings Like Elton John with his candle in the wind It's hard to blow out a flame as big as him But we've all got to Wang Chung with the Grim Reaper Whether you're Einstein whether you're Beaker Death is certain so it's definitely worth flirtin' Don't expect a bright light no just curtains Life is like a penis most people don't know it But most people suck so they usually blow it"
From "Take The Long Way Home", by The Bloodhound Gang