who would win?

Chopper, well, not in his regular form, but in Monter Point, HE!!S YEAH!

Chopper... when in monster form, there's no way some "ninja" can take him down.

A comment like that only shows me that you're being biased in your post. What do you mean that "some ninja" can take him down? It's all fine and all to have your opinion on this but don't be biased about it. You have to be fair to both sides of the poll.

It depends which form Chopper is in. If chopper is in his "human" form or his monster form, then I believe Neji might lose. Neji relies on accurately attacking chakra points with his Byakugan. Technically, since Chopper's not a ninja character from Naruto, he doesn't have any "chakra." so how would Neji deal damage to him? That would put Neji in a great deal of trouble during their fight, and ultimately Chopper would win.

I was actually just being lazy with my post. Chopper is a very underestimated fighter. In one mode he can detect everyone of his oponents strenghts and weaknesses, and dirive a battle strategy based off of what he read. And again, in his monster point mode, Neji wouldn't be able to put up a fight.