Myrdin> From what i remember about counter event girls:
Mountain Lily, Hyperloli, Mirabilis, Blanket Flower, Buttercup, Alyssum, Satsuma Mandarin, Olive, Sweet William Catchfly, Beardtongue, Echeveria.
I guess it's all. But not them all can do super counter.
edit: More precise data about Mountain Lily counter damage. I just checked and shecan deal ~22k super counter damage against thoses pierce-weak event halloween spider lvl72 raid bosses. Same with Echeveria (but with counter instaed of weak damage since she is hit type).
Mountain Lily is max level, max def ampies but not even max 2nd affection or got max level on all her equipements.
Add thoses damage with others counter damage and normal attack damageand they can do more damage in one turn tahn most of the other team type.