Say you want to pull a prank on the country and write in a silly name for President, like Donald Duck. How many friends would you need in order to get the attention of pollsters and maybe make the news?
In some states write in votes are not counted unless you are an official write in candidate - and to be official they have various rules on how you get to be an official write in candidate - some require petitions.
I’d never heard of that; usually a write-in votes are votes written in, and can be any eligible candidate (eligibility = they live in the district and are old enough if there’s an age restriction (say, for Congress)). They’ve been a part of balloting since paper ballots were invented.
Since write-ins hardly ever win, the parties aren’t threatened by them.
You do have to follow certain rules to get on the ballot officially (New York is famous for their complicated rules, with petitions invalidated because they were submitted too early in the day, or with a staple instead of a paper clip). But any citizen can write in a candidate.
The only potential exception is a write-in for president, since you’re technically voting for electors. You might be required to list electors in some states. But for any other office, you can writing whomever you choose and, as long as the candidate is eligible, the vote will count.
How do write-in candidates work at all, though? I mean, if I place a write-in vote for Charles Nordberg, how do they know which Charles Nordberg I’m voting for?
In Michigan you need to file a declaration of intent to be a valid write-in
You don’t vote for an individual for President in the first place; you vote for the slate of electors of that candidate’s party. So unless you have qualified a slate in that state or every state, your vote cannot mean anything, no matter how many of them there are.
For other elections, write-ins depend on state laws. If you’re seriously trying to write in a name, the more information you can provide to distinguish that person from others of similar names the better. I’d assume that a person waging a write-in campaign will have more luck in convincing a judge than somebody walking in off the street after the fact, but you have to know ahead of time that write-ins are tricky.
How many does it take to gain attention for a publicity stunt? That depends entirely on how good you are at publicity. There’s no possible factual answer to that.