Legitimate is an interesting choice of words, and could create a serious debate on semantics. But sure, it’s a political movement. It’s a third party as soon as they meet up and field some candidates. Getting on ballots varies by state and office, and in some cases is quite easy, in others very difficult. I would be surprised if they made it onto presidential ballots in all fifty states, just because most third parties don’t. On the other hand, they have some financial and media backing that no third party has had in recent memory. While I don’t agree with them in the least, I fully support their right to organize, field candidates, and get on the ballot.