Celtic, he had a pretty good fight but got sidetracked in thinking that it would be an easy kill after trapping the alien in the net. Obviously they either weren't taught that alien blood was acidic, or he just forgot.
Chopper is another story entirely. He just didn't see, nor hear, the alien behind him. He had both ears and eyes directed at Alexis, and was caught off guard. We've had something similiar happen to us.
As for an alien fighting a fully dressed and weaponed predator verus a naked (ew) predator, it would be an even/equal battle as the predator wouldn't have the advantage with the weaponry. He would still have his strength and his handheld weapons, such as knifes and smart disks, to fend off the enemy. But the point is that the predator would still have a hard time in fighting the creature.
Remember that these predators are over seven feet, and they must weigh somewhere between three hundred to five hundred pounds (including muscle). Add that to a battle with an alien that probably weighs the equilant of a grown man and you get the victor. Stamina might not be an option, but the sheer weight would quickly tired those poor predators out.
In predator years I would believe the predator in P1 to be in his 130's or 140's. The predator in P2 would be in his 120's and the predators in AvP would be like 118 or 119. Take the last two digits and you get the earth year versus the predator year lol
