A good coach uses the style of play that gives his team the best chance of being successful.
You don't have to push up defenders to midfield. Use your discretion with the players you have and push up to their skill level. It’s much easier for slow, unskillful players to be successful fullbacks if they “defend deep” and are given clear guidelines to follow. If you have fast, skillful fullbacks, then you probably should “push up” when you attack. However, all players should move with the flow of the ball.
The defenders should be learning to defend in "layers", or in other words, backing one another up. You can position one fullback 10 yards beyond the other. You can also have a skill player at halfback/stopper and have them back up the defender as well.
Match your defense to some degree to the skill level of the other team's forwards.
Learning to "READ" the field is the best asset a player can have, and it takes a lot of patience to teach this aspect of the game.
The midfielders need to be the players that can run the full field at least a few times without needing a sub. The other players need to handle the middle with triangles so each player has at least two ways to pass the ball.
Formations need to be flexible depending on the opponent. There is no one golden formation that works at all times.
In the intramural age-groups all players should be playing all positions.
Selecting Player Positions and Team Formations in Youth Soccer
When children start playing soccer at younger ages (U-6 Division), the emphasis is on small-sided soccer. At these ages, teams use 4 v 4 without goalkeepers. They eventually move to a 6 v 6 (including a goalkeeper) when they get to the U-8 Division. The small-sided game maximizes the number of touches each player gets, and also gives them an opportunity to understand the basic concepts of the game.
At these beginning levels, the players are just beginning to learn how and when to pass the ball, and you may have begun to introduce the concept of positions (for example, in 6 v 6 you may designate one or two players at a time to be defenders, or, to be certain that they get back on defense every time.
In the U-10 Division, the number of players on the field expands, and the size of the field expands. Now, there is a need to assign positions to the players and to be certain that there are players who defend and players who advance in an effort to score. You play 8 v 8 (including a goalkeeper) and it is often difficult to decide on a proper formation. For example, in 8 v 8 you may play a 3-1-3 or a 2-3-2. A 3-1-3 means (3) defenders, (1) mid-fielder, and (3) forwards. A 2-3-2 involves (2) defenders, (3) mid-fielders, and (2) forwards. You might also try a 3-3-1 or 3-2-2. These are stronger defensive formations and will certainly help to limit scoring chances by your opponent, which is important if you feel you are overmatched in a game.
There are advantages and disadvantages to all of these formations. For example, a 3-1-3 may give you a solid defense and a solid offense, but there is the risk of large gaps between the forwards and the defenders. This makes it difficult for the defenders to get the ball to the forwards, and leads to a situation in which three of your players are playing and the other three are watching and waiting. For example, either the forwards are working together in your offensive end to try and score while the defenders are standing and watching at mid-field; or, the defenders are fighting an attack while the three forwards stand near mid-field, waiting for the defenders to get the ball out to them. With a 2-3-2 the midfielders have to run a great deal. They will either stay close to each other and cover the entire width of the field, or stay just in front of the defenders, or stay just behind the forwards, often getting involved in the offensive third of the field. Triangles tend to be an important shape in soccer, for passing and support. The players can form triangles in several of the formations (2-3-2, 3-2-2, 3-1-3).
Whatever formation you decide upon, as a coach you will then need to communicate the concepts behind the positions to your players. Some players learn on the field. Others learn by looking at a diagram. Others learn well from reading and re-reading a textual description of their responsibilities.
You need to tailor the positions (defenders, mid-fielders, and forwards) to your particular coaching approach, philosophy, and formation. For example, if you decide on three mid-fielders instead of one of two, the responsibilities of the center mid-fielder may differ from the responsibilities for the outside mid-fielders. You may want your center mid-fielder to be aggressive on offense or you may prefer him or her to drop back on defense or to mark the other team's best forward or mid-fielder on defense. You probably want the wing mid-fielders, not the center mid-fielder, to take throw-ins. You may want your wing defenders to take all throw-ins. You may want your center mid-fielder or a wing mid-fielder closest to the corner to take corner kicks. There are many variations.