Sun Jan 15, 2017 11:45 am
Hmm it's hard to list everything. I just look at their skills/aura and see if it is good.
Off the top of my head, some like Marksman Luna (when she crits she has a chance to trigger others in aura to attack), Marksman Auron (when he crits he has a chance to trigger others in aura to stun an enemy for 1 turn) or Kensei Rin (when she kills an enemy she has a chance to trigger others to attack) have relatively good auras, whereas for skills - Winry have Stun or Sleep at a 5 turn cd, Marksman Auron with a 5 turn cd 2 turn skill delay or Lancer Fiona for the jump on a 5 turn cd (which is really good in gold mines) etc.
Zealot Leon also gets a special mention as he provides a lifesteal aura which is quite rare (only Black Knight Darrion and Samurai Miu has) and a pull which helps alot if you run 2 or more melees so you do not have to waste turns walking up to the boss (also disrupts aura formation in arena). Crusader Leon on the other hand is relatively tanky because of his persistent aura but I wouldn't just make him unless you are missing a Guardian. Besides, he might get a 5 star in the future so don't feed him away. (including Theia)
They can also help in some trials which require you to not use 5 stars. But I wouldn't prioritize them unless you are really missing a good potential 5 star class (like Guardian or Ranger so you make Leon or Luna respectively).