Nebula
Abilities: Nebula was trained and "perfected" by Thanos, meaning she's a highly skilled, half-machine assassin. Even before he replaced an assortment of her body parts with advanced technology, Nebula had naturally higher physical capabilities, including strength and durability.
Power scale: 5. We've seen Nebula snap necks and throw people around with one arm. She briefly held her own against Thanos in "Infinity War," and he even said that Nebula nearly managed to murder him when she snuck on board his ship. But we also know that Gamora has overpowered her in every fight they've ever had. Thanos' abuse took a significant emotional toll, which has likely bled into her efficacy as a warrior.