Alright, I think I've got a pretty convincing argument lined up here. My wife being a big fan of the show, and watching all the episodes multiple times with me in the room is finally paying off.
First things first, let's get three things that will be brought up for Twilight out of the way: the first being Twilight going "Ponyta" in the episode "Feeling Pinkie Keen". As was pointed out in the discussion topic, but I feel bares repeating, this is NOT Twilight showing the ability to suddenly shoot fire from her body. This was a cartoon visual gag, in line with a character's head turning into a steam whistle. It's not an actual ability of hers. The second is that bubble she produced in the episode that debuted today: "The Return of Harmony - Part 2". This point shouldn't be too confusing, but let's make it perfectly clear; said bubble was a bubble of friendship, as was clearly shown by it erasing a tiny bit of chaos when it landed on the ground. It is not a projectile shield that she can carry around with her. The third is Twilight's powers going haywire and superpowerful in "The Cutie Mark Chronicles", where she turns Spike from egg to huge dragon, her parents into stone, and does some other wacky, insane things before Celestia calms her. Now, this is obviously a latent power that COULD be delved into, but it's not really possible in this scenario. This only happened to Twilight during a time of high stress, while subsequently exposed to the Sonic Rainboom. While stress, if the battle were prolonged, would be possible, the Sonic Rainboom is not happening in this fight, period. Not to mention I don't think this fight would be prolonged. More on that in a second.
Next, there are no guns in the MLP universe. Bryan's pistol a completely foreign object to Twilight. That alone will cause her some problems, at least with sudden confusion. Now, if she could see the bullets coming, I have few doubts Twilight would be able to stop them. But that's just it; she won't see the bullets. Once again referring to "Feeling Pinkie Keen", Twilight was clearly shown to not have sufficient reaction time to avoid an opening door, even after ample warning from Pinkie Pie. Also, in the episode "Stare Master", while not shown on camera, Twilight is seen having been turned to stone by the cockatrice, meaning she was not quick enough (Or not knowledgable enough on the beast, either of which applies to this argument in the form of the gun) to avoid its gaze. This, combined with the general naivity that she is shown to have throughout the series (The best example of which would be "The Return of Harmony - Part 1", in which she can't sense something that is clearly wrong with her friends), makes the thought of her being able to figure out what a gun does and prepare for an incoming bullet coming in at ~950 MPH in the time it will take Bryan to pull the trigger very unlikely.
And there's an extra factor here as to why this wouldn't happen; Bryan would pull that trigger ASAP. If ANYTHING is shown in Taken besides Bryan Mills' perserverance, it is his quickness to react. He does not do the typical action hero move of letting the bad guy make a deal or do a monologue; Hell, he barely let's a single word escape the "final boss"'s mouth before popping him in the head. He would end the fight as fast as he could. You see, I do indeed think Twilight would win if this went beyond these first few stages. But it wouldn't.
So, in conclusion, I am under the firm belief that Bryan Mills would ultimately win this fight.
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Will not remove this line of my signature until the Seahawks, Jazz or Rockies win a title (Started 5-16-09)
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