Iron Man's repulsor technology and sonic weapons perfectly counter Venom's symbiote weaknesses.
Iron Man's technology gives him significant advantages against Venom. His suit's repulsors generate intense heat, his unibeam can reach extraordinary temperatures, and Tony is smart enough to quickly identify and exploit the symbiote's fire and sonic weaknesses. Friday or JARVIS would analyze the symbiote within seconds and recommend optimal countermeasures.
Tony's suit also grants him flight, keeping him out of Venom's close-range grappling range. From the air, Iron Man can bombard Venom with repulsor blasts and sonic weaponry while staying safely out of tendril reach. His suit's strength in the higher-end models also matches or exceeds Venom's, removing the symbiote's physical advantage.
Venom's path to victory requires getting inside Tony's armor โ the symbiote could theoretically infiltrate the suit's systems. But modern Iron Man suits are sealed against biological and chemical intrusion, and Tony's AI would detect and counter symbiote infiltration attempts.
Iron Man's repulsors generate extreme heat exploiting Venom's fire weakness, his suit can produce sonic frequencies targeting the sonic vulnerability, and his flight keeps him safely out of Venom's effective combat range.
Venom's symbiote could theoretically infiltrate Iron Man's armor systems, and in close quarters the symbiote's strength and tendrils could grapple and damage the suit before Tony can deploy countermeasures.
Iron Man wins through technological counters to the symbiote's weaknesses. Tony's intelligence and suit capabilities are perfectly suited to exploiting Venom's vulnerabilities from a safe distance.
Iron Man also fights
Venom also fights