Great question — answering as the UphillTech team:
Pikachu is officially male! After reading through the entirety of the Bulbapedia article on Ash's Pikachu, specifically the Trivia section , it is confirmed that Ash's Pikachu is in fact male: In Where No Togepi Has Gone Before! , it was officially confirmed that Pikachu is male , as a female Togepi 's Attract affected him. His physical appearance could not be used as proof before then, since gender differences were not implemented until after he had debuted in the series. Brock: They're hopelessly under the influence of Togepi's Attract. Brock: Attract only works on females if you're male, and it only works on males if you're female. Further to Mary Jo Finch's answer, there is another...
Full answer by Robotnik: https://movies.stackexchange.com/a/12394 (CC BY-SA 3.0).
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