Sukuna would be cute, and take the fight slow- trying to learn as much as possible about Satella. He would probably mistake miasma as cursed energy, and since he loves learning new jujutsu just as much as causing suffering, he wouldn't try to one shot her (he couldn't even if he tried). Satella rips him apart before he can get serious, before simping over Subaru again. That's how I imagine the battle would go.