The Energon Pub

[Gyro-Robo]

As in the alien called Predator.

[Blurrz]

Ben could probably just transform into one of the physically big Aliens in the Omnitrix and crush a Predator.

[Psycho Warrior]

Ben's an idiot, The predator's not going to announce his approach and normally only needs one attack to end the hunt. If Ben's quick enough he could avoid it. But in my opinion that's a big if.

[Lastjustice]

Is this younger or older form? If he's a kid, the predator likely wouldn't attack him due to their honor code unless he was already in some sort of form that was worthy of combat. Unless the Predator knows what the omnitrix is, it wouldn't see Ben as being armed, and wouldn't attack him anyways. Predators never intentionally kill noncombatants.

[Armorock]

I believe Ben probably should win, but he probably wouldn't. Against, say, Big Chill (especially Ultimate) or maybe Lodestar and WayBig, Ben could win.

Knowing Ben, however, he would probably turn into Cannonbolt, Humongusaur or the increasingly popular Rath, Ben would probably wind up with a few laser shots through his eye.

[snavej]

P wouldn't fight immediately. He would spy on B and learn his ways. He would steal the Omnitrix and kill B. P wins.