Well then, have you heard or watch Sadako vs. Kayako film where story revolved teens whom on the run from Sadako's spirit and eventually resort to trick her to fight against Kayako Saeki to end both curses?
Anyway, the fight between Kayako and Sadako was quite anticlimatic and many people disappointed with it. For me, in order to make the fight between those ghosts more interesting and brutal, it should be like this:
Kayako pounches Sadako and seemingly killed her by breaking her neck like a twig, mistaking her as a human. As Sadako seemingly defeated, Kayako turned on both Yuri and Suzuka, intended to kill them too. However, Sadako unexpectedly stand up (still with broken neck) behind Kayako, formed a large drill-shaped tendril from her hair, and impaled Kayako through her chest with it! Sadako then lift the helpless Kayako to the air, fixing her broken neck with her hands as she simultaneously stabbing her drill-hair even further through the chest. Sadako proceed to put one hand to Kayako's right shoulder while another to her ribs. Then finally, after glaring, Sadako completely tears Kayako in half, leaving both the upper body and lower body to fall on the ground. But Sadako seemed not satisfied as she impaled Kayako's left eye with her drill hair again and tear her into shreds. This caused both girls to flee.
Sadako then chased the girls, but Toshio, whom escaped from the television, unexpectedly jumped to her back and attempted to broke her neck. This enraged Sadako that she tossed Toshio aside, and slammed the ghost boy to the floor with one lashes of her drill-shaped tendril hair, resulting the floor below him shattered in process. Before Sadako delivered a final blow to Toshio, Kayako, whom fully regenerated from being torn into shreds, showed up and pinned Sadako to the wall with strength of 10 men at the last seconds, saving Toshio and smashed the wall behind Sadako into pieces in process. Kayako's counterattack made Sadako become disoriented, allowed Kayako to break Sadako's neck yet again, but this time, Kayako ensnared Sadako with her own hair, lifts the opposing ghost over herself, slamming Sadako's face on the ground, breaking her jaw. As Toshio used the opportunity to retreat, Kayako lifted the already-battered Sadako by the hair, before formed her own drill-shaped hair tendril to impale Sadako through her skull.
As Sadako seemingly destroyed by Kayako, Keizo tossed Sadako's cursed tape to Kayako whom proceed to break it. But Sadako immediately recovered from the injuries and stopped her from shattering the tape. By the time the protagonists on the outside and prepared the well, they can hear loud noises from the house, started from one of the windows of Saeki's house explodes to the outside.