I've been looking around and noticed that this topic was touched in various other threads, but never gone into.
I'll name a few basic types of djinn tactics and combos

Chains: These long combos require careful planning if one character uses their djinn or summon to early or late it could ruin the whole chain. These are ill advised against enemies like the doom dragon and Dullahan (due to Mass Djinn Recovery Attacks. AKA: Djinn Fest, Djinn Blast, and Djinn Storm)

Combo: Two or three djinn used together. Often involving Lull, Reflex/Flux(which is it again), kite, and etc.

Tactics are slimply djinn setups, and the usage of djinn and summons to gain an edge over an enemy.

I'll through a topic out there (but if you would like to discuss another your welcome to throw it out there).
SO... How about my personal favorite: Jupiter combo's and chains?

I have Felix and Jenna and Piers, or Isaac and Garet Mix, or a mix of three, use their defensive djinni, one per turn, while the others assault the enemy. Then when I am on the last of the three defensive djinni, I have one of the others bring theirs out of standby. So I have a defensive and offensive tactic.

where do i get the iris summon?
i know i need every dijinn in the game the ones from golden sun 1 clear data

Yeah, this is pretty much everyone's favorite combo, but I'd have to say RNG methods.
Oh, someone asked what summon Dullahan is guarding?
Well, it's called Iris. Not only does it deal massive damage, it also heals completely and revives all downed characters.
Meh got a knife!

Oh, wait. Iris is in Anemos Inner Sanctum, along with Charon. But the only difference is that you can get Charon for free.
And you have to beat Dullahan to get Iris.

i use whatever i get to get iris use telaport in contigo then go to the things

My favorite is to use Shine to dazzle enemies, then I slam then with a ton of Meercuty Djinni.

Gotta hate necromancers, though.

inb4 lock