What is is pikachu a boy or a girl?

Pikachu's gender is intentionally ambiguous in the Pokémon anime and video games. While early merchandise and promotional materials sometimes leaned toward a male portrayal, the official stance is that Pikachu is designed to be gender-neutral and appealing to all audiences.

Notably, you can determine Pikachu's gender in the video games starting from Generation IV (Diamond, Pearl, and Platinum). Female Pikachu have a heart-shaped notch at the end of their tail. Male Pikachu lack this notch and have a straight tail. However, this visual cue is only present in the games and not in the anime.

So, in the anime, Pikachu is generally considered gender-neutral, while in the games, there is a distinct visual difference allowing you to identify male and female Pikachu.