Firstly, the most important thing: Yes, there are goofy looking lizard monsters in Fallout: New Vegas.

Secondly, while it is possible to beat the game without killing anything, it will at times put you in a position in which either you don't help people, or you help them kill something while letting them get the actual "kill" (the game keeps track of all your kills except for robots).

This is a bit more forgiveable than running around with a sniper companion who kills everything for you, but it's still a bit iffy from a "no, really, I'm a pacifist" perspective. From a "gameplay challenge" perspective, however, it's all in good fun, and part of the challenge.

That said, one way you can help NPCs with armed enemies is by shooting weapons instead of people. For roleplaying purposes, you may then proceed to say "no, stop fighting, I shot the guns out of enemy hands so we could make friends" or something. This strategy is less helpful when dealing with goofy looking lizard monsters.