Here is a list of Servants with Brynhildr’s Beloved trait. Those servants are weak to Brynhildr's Noble Phantasm, Brynhildr Romantia.
Rashoumon event (Ibaraki Douji event)
Murder at the Kogetsukan
Inheritance of Glory
EMIYA
Cursed Arm Hassan
1st Singularity: Orleans
Mysterious Heroine X (Assassin)
Medb
Sakata Kintoki (Berserker)
Ereshkigal
Arthur Pendragon(Prototype)
Gorgon
Black Holy Grail (The Black Grail)