1) must be true anytime. As for 2) - 4), it depends on situations. In my opinion.

がんばってください

Ruin 's notebook entry: Jul 25, 2010 - Which is the best fo "Two moons"?

Hmmm, which would be correct here to say the phrase "Two moons"?

1) 二つの月
2)月が二つ
3)月は二つ
4)月を二つ

Babel fish suggests option 1, but I would've thought that either of the latter three were correct. Please reply to this very soon, if you can. ありがとうございます

It depends on the situation. If only "Two moons" as noun and not to be subject for the sentence, opt.1 is correct.