I feel teams became incredibly simple once I started following a few basic principles. I am not really certain where to start with mentioning these traits, so I will put them out there in really no order at all.
- There is often a TON of waiting in smash even in Melee where its pretty fast paced. Try to use that time wisely by prioritizing your time. People are likely going to come back to the stage and you cannot guarantee success at KO'ing them with how good recovery is in this game. If your teammate is in trouble forget the person you just sent flying super far offstage. Go help your teammate by either hitting the other person or giving them something to worry about.
- 2 v 1 situations are pretty good. Ideally, even if your opponent hits one of you there would be another person to punish the person who hit your partner. What is better is that through your combined actions near a person you can cover everything they can do. If they roll in either direction you got it.
- Designate who gets point. Its teams. If your partner is hit there is the other person to follow-up to punish the person hitting your partner. Not advancing is bad because you both get caught at the side of the stage and get bunched up getting in the way of one another. Person in front should take point even if you might risk getting hurt because you NEED that space else the alternative is worse where you both hurt each other.
- Try to line-up 1v1 match-ups if you can at all, but it will not always happen. I mean try to 2 v 1 a target and another person designated as the left-alone. Your team's best character against the left-alone will act as a more passive role. This person will try to wall out the left-alone enemy while covering options of the other opponent. Your teammate will act as the primary aggressor against the target.
The left-alone is generally the weaker character that cannot intervene as well. Either through play-style or their character. The target is the harder of the two, but should fall prey to a 2 v 1 pincer attempt. Every character has lag and cannot truly defend against a 2v1 situation. But, since you have your better character acting as the wall to the left-alone you have a pretty strong situation.
However, all of this strategy is meaningless if neither of you can equally be good players to carry it out. If your teammate gets knocked away and you never punish the opponent for doing it your 2v1 pincer was sort of useless. The strategy can help set you up for success, but it still comes down to several scenarios as characters, percentages, stage, and player skill.