Estelle- Princess. Not terribly fond of her in the main story, too... damsel-y. Good skit character though.
Nightingale. Really all that needs said. I suspect that she actually has some lategame potential as a fighting character with Extra Hits, but eh.
Middle. Healing isn't terribly good for duelling purpose (pricy) but it's there, but more importantly she's got the anti-Magic option and while she's more of a Light against physical fighters, she doesn't instantly lose to them either and her durability and auto-revive gives her wiggle room.
NO.
You seem to forget that 1. she can't die while in guard 2. she has auto counter in Guard Reflect, Pain Reflect and Pikohan Revenge 3. She has break suppress 4. She has Super Guard and Super Resist 5. She has Angel Recall 6. She has Revive
What does this mean??
Thanks to Break Suppress, knocking her out guard has become terribly hard, aka she can't die, which also mean those who can't not knock her out of guard well die of her counter sooner or later.
Than the effect of Super Guard or Super Resist, by making the damage taken from magic and physical to be reduced to one when guarding in exchange for double damage taken when not. This basically means no one can ever guard breaks her, NO ONE, unless you have none type damage. AKA, they'll eventually die to counters from Pikohan, and OVL gauge increase when attacked too so Estelle can throw in OVL combos or Hi-Ougi once a while after tanking enough. Then there is Anti-Magic to shut off most status, and ToV guard prevents status from physical unless guard break. And Angel Recall is there as a safety measure, combine that with Revive, she can even purposely eat big damage from enemy and have her opponent eat a part of it through Pain Reflect.
Even a good number of high godlikes is going fell before her, so no, she is most definitely NOT middle.
Also, on Karol's damage. Might Charge really is not the primary factor. Second Hit and Down Burst is the real gold here. Try to knock the enemy down to floor with your first arte, and the rest can make your opponent bleed. Then combine with Break Down to keep them on the floor longer... the real trick is to figure out how long each attack can keep the enemy on floor on long they can stay down after a certain number of hit. Usually, the initial down is very short and have a down time extension with the first 3 consecutive hits. If you do it right, you can combo loop enemy by constantly extending their down time.... just you really wouldn't be bothering doing this when you can just spam away with Yuri.
Oh, BTW, Yuri's Hyper Combo does not go by the normal combo count, which means he can still go OVL even combo got disrupted. Hyper Combo skills follow a more lenient internal combo that still counts your hit if it fail to stagger the enemy or enemy broke out with auto recovery.
