1: Hulk:
I say a draw. The Hulk can only use physical attacks (excluding the thunderclap, but I doubt that's be effective), and Luffy can survive those. On the other hand, I can't see Luffy doing anything that could tickle the Hulk; he regenerated from a skeleton for crying out loud!
2: Batman
Yes. If Batman was unprepared, Luffy would win in two seconds. If Batman was prepared it'd be like Luffy vs. Usopp, where one sucesful blow ends the fight.
3: Goku:
Yes, Supposing that ki-energy has the same efect as Enels' Electric energy.
4: Dredd: Easily.
5: Mr Fantastic
Yes. Luffy has one move that could make him win: Baku Baku.
6: Chuck Norris. Yes
7: The Flash
Yes. Luffys' kept up with Kuro and Cp9'ers, so I can't see why not.
8: Neo. Yes
9: I don´t know him.
10: Naruto: Most definetely. He's both Stronger and faster.
11: Ichigo: I haven't read enough bleach to know.
12: Samurai Jack: Yes. He kept up with Zoro at Whiskey peak, and now he's got Gear.
13: Spider-Man
Yes. Poor Spidey wouldn't know what hit him, and mantra-like spidey sense aint' going to save him.