Shut-Outs are games where you don't allow your opponent to score the entire game. Another way of phrasing a shut-out is a win without conceding a goal.
This is one of the achievements in the Arcade mode, and is used to unlock Germany. You unlock Germany by shutting out 10 different opponents. There is also an achievement to unlock United Kingdom which is very similar, which is win a tournament without conceding more than 4 goals. Both of them are good characters, so shut-outs really are important. Another reason to try to get shut-outs is that when your trying to go through as many games possible as fast as possible for something like unlocking Super Saiyan, the game goes faster if you shut your opponent out. The game pauses for 4 seconds after every goal, so if you could win a game 2-0 instead of 9-7 you would save yourself practically a whole minute.
Here are a few strategies to win games without allowing goals:
1) Germany/France 1-0 WinsEdit
This is probably the least reliable method, but it can be used to consistently waste the first 20 or so seconds of the game, so I will still put it on here. To do this 1-0 win, you will need France. At the start of the game, simply run at you opponent and just kick him into the back of the goal you're trying to score on. Once you get it, activate your Power Button up, but don't use it. The goal is to keep kicking your opponent into the goal and then with about five seconds left run to the ball. The ball drops straight down at the start of the game so you won't have to worry about it moving. The reason for France is that if you use France's Power Shot from the exact center line, it is a 100% goal. The ball goes underground and comes back up right in the net. The reason this strategy doesn't always work is because your opponent will kick back. Sometimes they will stun you and kick you back into the ball, but if you have your Power Button activated you should still score putting you up 1-0 with half of the game wasted.
2) Sit 'n' WaitEdit
This is another unreliable method, but can be used a good bit. It doesn't really matter which Character you use for this shut-out, but you should use a character like France or Luxembourg that can score in the last few seconds from midfield. The idea is that you run up to where the ball will drop at the start of the game, and if your opponent just stays by where they started, then you can just wait there. Make sure your standing right next to where the ball will drop, but so that when it drops, you're in between the ball and your goal. Germany is recommended, because sometimes when your opponents activate their Power Button they will begin to run at the ball and if you're Germany you can just step forward using your power shot, not only wasting theirs, but also putting you up 1-0 about half way through the game.
3) Jump OverEdit
This is one of the most favorite methods, and probably the most reliable. At the beginning of the game run up to the ball. If your opponent stays back, then you should transfer to the Sit 'n' Wait, but if they come to the ball as well, then try to jump over them. Obviously this is slightly easier if you are wearing a costume that helps out your jump. Once you jump over them, dash back towards your own goal a few times. You should be able to do all of this before the ball drops on your heads. After dashing back and letting the ball fall, from one side of the screen to the other it should be: your goal, opponent, you, ball, opponents goal. Now simply walk back into your own goal. This will push your opponent back along with you. No matter how many times they dash or kick they should not be able to get out. Every once in a while they will jump, but then they should fall back to the ground. If they don't then you need to do something like jump to stay in between them and the ball or run towards the ball a little so that they can complete their jump and then walk them back towards the goal. Most of the time you should be able to hold them there for the entire game. With about 3 seconds left, run up to the ball and score. This can be done by dashing, or kicking, whatever just don't activate your Power Button up for the whole game. If you go at 3 seconds then you should be up 1-0 with 2 seconds left and your opponent will have a power shot. At this point, you have won as no Power Shot can score with only two seconds left. This technique can be done with any character.
4) Mexican First GoalEdit
This obviously requires you to have Mexico. It is recommended to have a costume that boosts Power Bar a good bit for this one. Basically, all you need to do is score first. After you score first, you and your opponent should almost have a power shot. (If you're wearing a power-friendly costume.) Unless you're playing Germany or Spain, wait for them to use their Power Button Effect up. Then simply activate yours and use it to block theirs. Try to use Mexico's Power Shot from as close to your own goal as possible. Then the giant hand will grab your opponent and will throw him into the grown by your own goal. During this time get in between your opponent and the ball. Now since Mexico's Power Shot throws the ball straight into the air, you shouldn't have to worry about it moving, so you can simply walk your opponent back into your own goal just like the Jump Over, except this time you don't have to score at the end.