SupermanvsVenom

This is a massive mismatch. Superman operates at a planetary to stellar power level, while Venom is a street-to-city level threat at best. Superman's heat vision alone exploits Venom's weakness to fire and extreme heat, and his speed means Venom could never land a blow.

Venom's symbiote physiology is vulnerable to both fire and sonic attacks. Superman's heat vision is hotter than the surface of the sun, and his super-speed punches create sonic booms. He essentially has both of Venom's critical weaknesses as standard attacks.

Even ignoring the symbiote's vulnerabilities, Superman's raw physical stats dwarf Venom's. He is millions of times stronger, infinitely faster, and virtually indestructible by anything Venom can bring to bear. The symbiote's shapeshifting, tendrils, and regeneration are impressive against street-level heroes but meaningless against Kryptonian power.