Throughout Avengers Infinity War movie, we see Thanos fight with one or more Infinity Stones. So he's using their power to win against the Avengers. But does he have any superpowers without these stones or is he just a skilled fighter strong enough for his size.
Although Thanos' backstory is not covered in the MCU, he is an Eternal,
Thanos possesses the superhuman physiology of all Eternals, granting him superhuman strength, endurance, reflexes, and agility. His skin in nearly invulnerable, particularly against heat, cold, electricity, radiation, toxins, aging, and disease, and he can survive indefinitely without food or water even before his "curse" from Death left him immortal, unable to die. His mind is also invulnerable to most forms of psychic attack, and can project a psionic blast of energy as well as blasts of plasma/cosmic energy from his eyes and hands.
Also a Wikia
Deformed Titan Physiology Thanos is noted to be extremely powerful Titan, so much that he is able to strike fear in the hearts of all of his children and even Loki himself. He even showed no signs of fear upon being threatened by a Infinity Stone empowered Ronan.
- Immortality: He is an extremely old being and has been called almost impossible to truly kill.
- Superhuman Strength: He has tremendous amounts of bone and muscle power, which was seen to surpass the Hulk's extraordinary physical power and beat him into unconsciousness.
- Superhuman Durability: His physical constitution is extremely durable, being able to wield the power of all the Infinity Stones and physically touch them without any damage or injury. He could even take on tremendous amounts of physical damage and still continued on with his mission.