OK, speaking up as moderator here.
I'd like to think that it's a given that the rules of the TOS apply here (no graphic images or spam) as well as a code of civility. My own posts tend to have a little vinegar in them when I'm trying to get a point across so I tend to be laissez-faire unless something is really over the line.
Getting that out of the way, here's how I run this show:
Past Election What-Ifs?: Questions about former elections and possible counterfactuals go here. (Ex: John F. Kennedy in 1964?) Posts made in the main board about such possibilities will be moved here.
Alternative Elections: Discussion about possible future elections will go here. (Ex: Carson in 2016?) Posts made in the main board about such possibilities will be moved here. (ibid)
International What-ifs: "Discussion of alternate possibilities in international elections." As it says on the tin.
As long as we conduct ourselves in this manner, this will leave the main board free for timelines and interactive games.
EDIT: Absurd match-ups: For awhile there was the pervasive problem of some posters making impossible match-ups (Ex: Superman vs Batman.) These will be treated as spam and deleted unless it prompts an intelligent discussion.