Hey, really liked your thread, since I'm a huge fan of team building as well. Here's my own take on team building, based off a few things you have mentioned. It basically involves 3 points: Purpose, Positioning, Timing. (Tried really hard to get a third P but meh.)

Purpose

Before starting on any team, have a clear purpose on what your team is for. Similar to finding a team that suits your play style, building a team to use a particular ninja effectively c*so be quite devastating. A common example will be the "Lightning Blitz" meta that needs no further introduction. Otherwise, having a group of ninjas that can work effectively together c*so be really powerful. A lineup similar to the wind meta (Kazekage Gaara, Sage Naruto, Gakido) would be replacing Gakido with Sailor Sakura, possibly giving double heal in 2 turns when coupled with BD's DoI. This grants greater surviva-bility for team who lacks a healer. There are of course, trade offs in both lineups.

Personally, while having a high combo team is a certain playstyle you c*e, it is something that has proven to not be very useful, if the team doesn't fill a second purpose. Bringing ninjas with 2 chases as a part of their skill can result in a 10 combo chase which can be devastating, but you will come to realise that in higher levels, these types of teams can be relatively easy to shut down with any status effect like immobilize, paralyze, sleep etc. (Eg, Karin, Sasuke, Hinata) Hence, finding ninjas whose passives pair up well together is key. Most team compositions can have their combos linked together through the use of summons and the Main Character chase.

After putting the theory together, it is always good to get practical and try out your lineup in arena or against your fellow group members to see how well you fare, to identify any potential flaws you missed while fighting against all sorts of lineups.

Positioning

After finding your lineup of 4 to use in battle, how your ninjas are placed in the 9 grids is also fairly important. Most ninjas in the game have a habit of attacking whoever is infront of them, except a select few. In other words, the ninja most commonly standing in front of the enemy have the highest chance of being hit. This can be substituted with a tanky Sage Naruto clone, or even a tank in general, like Kimimaro. If your team plans on maximizing this standard attack damage, placing ninjas like Kimimaro where he has the highest chance of being attacked by the enemy can work to your benefit.

Another way to see it would be to see which ninja is the most dispensable. Which ninja can die without having too much of an impact on the team? It is undeniable that it is near impossible to shield every single ninja of your team behind an unsinkable tank. Hence, knowing which ninja is the least useful and purposely leaving that ninja open while you do damage to their key ninjas can help you turn around a losing battle.

Of course, if you understand how initiative works in the game, it would not make sense to leave your combo-starting ninjas at the back, as the 4th ninja to move. The saying holds true for most cases: 'He who strikes first wins'. While it is not completely essential to have your ninjas to be in front and possibly put it at risk of being attacked, it does hold a certain advantage to attack early on, especially if your opponent's team does not have ninjas who can clear your debuffs. This will be elaborated more upon next.

Timing

Now that you've figured out your team, and have set a satisfactory position for them, there comes the last part of pitting your team against your opponents. This part requires quite a bit of game knowledge and understanding of the ninjas in the game. First off, *ysis. Take a good look at your opponent's team, and try to figure out his play style, and weakness. Who is the core of the team holding his combos together? Which of his ninjas is the most dangerous against you? Figure out which ninjas should have a higher priority in your kill list.

Next, figure out whether your opponent have a higher initiative over your ninjas. While your opponent might have a higher overall initiative, they might not necessarily have higher initiative over every ninja. This can be easily determined by looking at the first round. In the first round, who moves first when it comes to doing their respective standard attacks? Did your position 2 Sage Naruto move before your opponent's position 2 Mifune? If so, you will have higher initiative when it comes down to using your mysteries on the next turn, assuming that Mifune is going to use his mystery next turn as well. Knowing this can help you plan ahead of the battle, If your ninja can interrupt or stop short of your opponent's mystery, or whether to even use your mystery if you know you are going to be interrupted by your opponent instead. In this scenario, it might be better to wait for your team healer to remove the debuffs before proceeding on with your combos. Otherwise, putting off your mystery for another so that you can have the initiative next round in your mystery c*so help.

For example, both your P1 and P2 ninjas are slower than your opponents P1 and P2 ninjas. On the first set, your opponent triggers his P1 ninja, while you trigger P2 instead of your P1. This gives you an advantage on the second turn where you can trigger P1 and move faster than your opponent's P2, even though he has higher initiative than both your ninjas.

This essentially delays your combo for a better opportunity later on. It is worth noting that this type of *ysis can be seen through and used by your opponents as well.

While talking about healers and delaying your combos, a practical application to this would be against heavy healer teams. (This is inspired by Hanzo SA, if you're curious) Waiting for your opponent's standard attack heals to happen first (Similar to waiting for Shizune's heal) before unleashing your combos, and repeating this next round before the opponent's healing mystery is triggered next round (Again, similar to how you kill Shizune) can quickly break apart these healer teams. This is compared to mindlessly trigger any mysteries you have immediately at the start of the round, just to watch your opponent heal the damage away as if nothing has happened by the end of the round.

End

The fun thing about team building is that each team can be very fluid in their own ways, and you have to adjust your playstyle according to each opponent. Even against the same lineup, different initiative between ninjas can make a difference. Certain parts of this post may seem repetitive of the original post, but I tried not to mention the same things as the original author. Hope this helps whoever reads, even if by this a little. Cheers.