Hmmm… for each of the characters…
Mardek: He has rather high HP so he doesn’t need any green stoles You can arguee for either the scarlet (to increase his attack power), or azure (to increase his heals)
Donovan,Sharla: Azure is probably best.
Ss’lenck: He has high HP and a high natural strength, as well as a high attack weapon type. He doesn’t really need a stole (what he needs are those boots that increase agility by 10.)
Solaar: Either green to boost that HP, or azure to make those light attack spells even more powerful. For a laugh, equip the steel stole, and then cast astral form. Solaar will then proceed to ABSORB PHYSICAL ATTACKS.
Elwyen: I guess azure, since she can use her songs rather effectively with high spr?
Gloria: azure, definitely. It’ll also increase the defense boost that barkskin gives.
Meraeador: I honestly haven’t considered using him as much of an attacker. The way I used him didn’t really need stats… I suppose you pick whatever stole is best for what inventions you give him, and if you want him to be defensive, then give him a green stole?
Zach: Scarlet. As if Crescendo Slash wasn’t enough of a snowball!
Vehrn: You can either give him a scarlet stole (since a lot of his attacks are physical), or an azure stole (His “Smite +” and “Smite X” attack reactions work off his SPR stat.. And also his level, in Smite +’s case. Even back in chapter 2, that was over 100 extra damage every single hit, as he gained levels!)