Gonna talk about Kashimo's technique.
The name is a reference to Kashimo's time period. Amber in the Japanese Middle Ages was the stone of the Japanese Imperial family and represented having the blood of the dragon. Japanese dragons were storm dragons and river dragons, and it was believed lightning storms were dragon battles. In other words, Kashimo's technique is to become the most powerful and divine thing of his period, representing how he was the strongest of his time.
Note that he has dragon horns, claws, and breath weapons. Overall, dude is a lightning dragon in human form. It makes sense why he could destroy a weakened Sukuna in three hits and a lightning bolt — his has an insanely high level of attack power, probably as high as Gojo's Purple, though far more constrained in terms of range.
Let's talk about the attacks too.
When Kashimo had his palm in Sukuna's face, Sukuna dodged instead of blocking. Why? Because this wasn't a sonic attack. This is right when we get told that Kashimo can also fire off electromagnetic waves. These are basically waves of light that tears apart matter. It's one of the highest AP attacks we've seen in the series. Like, it isn't Infinite Pressure (like true sphere) or a Black Hole, but there's no way to defend against something like that. This is why Sukuna specifically dodges that blast, unlike the sonic one from earlier.
Furthermore, Kashimo is tricky. After he fires the wave, he turns to scream at Sukuna. In order to block the scream, Sukuna needs to protect himself with both of his arms (a sonic blast striking his torso would be way more damage then striking his arms). However, even though Kashimo screams, he's so fast that he can juke Sukuna out, punching him instead of blasting him. This means that Kashimo's reaction speeds are truly some of the highest we've seen. He has extremely powerful punches, sonic blasts, and deadly electromagnetic wave blasts, and he can rock-paper-scissors you into defending one of them only to be hit by another. It makes him incredibly lethal.
I think with all this considered, in terms of 1v1, Kashimo = Gojo, but Gojo's domain and six eyes means he'd probably > Kashimo. But Kashimo's binding vow here is powerful. After using his technique, he crumbles away. The combat power Kashimo wields is truly fucking enormous because of this.
I think he should be considered comfortably above everyone but Kenjaku, Gojo, Sukuna, and Takaba right now.
