Here's a guide to a few basic clan war formats. If I forgot something about a specific format, or didn't include one, then feel free to PM me about it or post something here, and I'll add it to the guide.
Elimination
How it works.
Elimination is just a fancy term for last man standing. There can be as many people on each side as desired, but it's usually 5 vs. 5, 6 vs. 6, or 7 vs. 7. Each match is best two out of three. If you lose, then you're out. If you win, then you can continue to fight for your side. The sides continue to fight until one side doesn't have any people left, and the other clan is the victor.
Pros.
-Every clan is familiar with this format.
-Easy to organize
-Easy to execute
Cons.
-One great brawler can win the war for their clan, even if the rest of them lost.
-If you're not comfortable with one on one, then you're out of luck.
Moon's Tennis Format
How it works.
Three people on each side are needed for singles, and four people (two teams of two) are needed for doubles. The clan that wins three or more of the matches wins, whether singles or doubles. All matches are best two/three, three stocks, and the doubles matches have Team Attack on.
Pros.
-Uses both singles and doubles matches.
-More people get to participate.
-Isn't dependent on one person, but the whole clan.
Cons
-No flexibility when it comes to the number of people on each side.
-Other clans usually aren't familiar with it.
Points/Round Robin
How it works.
Points is a format that uses a point system (nowai!). It's three stocks, one match per opponent. Each participant faces every person that's on the opposing team. Each stock you take counts as a 'point'. So if you beat your opponent, but they take two of your stocks, that's three points for your clan and two points for the other clan. At the end, the clans tally up their points and the clan with the most points wins. Each side can have as many members as desired.
Pros.
-Each stock is worth something. (Ex: in elimination, it doesn't matter if the person is three stocked or it's a close match.)
-No one has to worry about who's facing who.
Cons.
-Hard to organize.
-Ties are possible.
Crew
How it works
Crew style is similar to elimination. However, the difference is that you don't regain stocks. If you win your first match with two stocks left, your opponent is eliminated, and you have to face the next opponent with two stocks while they have three. (Or however many stocks was agreed upon).
Pros
-Each stock is worth something.
-Even if you lose, the stocks you take can help your teammates.
-One good player probably can't dominate, because eventually they'll run out of stocks.
Cons
-Really good players needed on our side.
-YOU CAN'T GET THREE STOCKED.
Elimination
How it works.
Elimination is just a fancy term for last man standing. There can be as many people on each side as desired, but it's usually 5 vs. 5, 6 vs. 6, or 7 vs. 7. Each match is best two out of three. If you lose, then you're out. If you win, then you can continue to fight for your side. The sides continue to fight until one side doesn't have any people left, and the other clan is the victor.
Pros.
-Every clan is familiar with this format.
-Easy to organize
-Easy to execute
Cons.
-One great brawler can win the war for their clan, even if the rest of them lost.
-If you're not comfortable with one on one, then you're out of luck.
Moon's Tennis Format
How it works.
Three people on each side are needed for singles, and four people (two teams of two) are needed for doubles. The clan that wins three or more of the matches wins, whether singles or doubles. All matches are best two/three, three stocks, and the doubles matches have Team Attack on.
Pros.
-Uses both singles and doubles matches.
-More people get to participate.
-Isn't dependent on one person, but the whole clan.
Cons
-No flexibility when it comes to the number of people on each side.
-Other clans usually aren't familiar with it.
Points/Round Robin
How it works.
Points is a format that uses a point system (nowai!). It's three stocks, one match per opponent. Each participant faces every person that's on the opposing team. Each stock you take counts as a 'point'. So if you beat your opponent, but they take two of your stocks, that's three points for your clan and two points for the other clan. At the end, the clans tally up their points and the clan with the most points wins. Each side can have as many members as desired.
Pros.
-Each stock is worth something. (Ex: in elimination, it doesn't matter if the person is three stocked or it's a close match.)
-No one has to worry about who's facing who.
Cons.
-Hard to organize.
-Ties are possible.
Crew
How it works
Crew style is similar to elimination. However, the difference is that you don't regain stocks. If you win your first match with two stocks left, your opponent is eliminated, and you have to face the next opponent with two stocks while they have three. (Or however many stocks was agreed upon).
Pros
-Each stock is worth something.
-Even if you lose, the stocks you take can help your teammates.
-One good player probably can't dominate, because eventually they'll run out of stocks.
Cons
-Really good players needed on our side.
-YOU CAN'T GET THREE STOCKED.