His weakness is the Needle Cannon, but he can also be easily defeated using the Mega Buster. He is also weak to his own weapon, the Search Snake, but it can be only used in the rematch against him in Wily Castle.
expressly, What is Gemini Man’s weakness Mega Man 3?
Gemini Man also has a hatred and fear of snakes, mainly because his weakness is the Search Snake.
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