It looks like Pikachu's take on traditional Japanese hair ornaments. You can tell it's female because the tail tip is rounded with a notch in the middle, making it look like a heart (see 3:02-3:13 in this video). The flowers make it more obvious to non-fans. Without them it's harder to tell, though they mirrored the tail. See also spiky-eared Pichu.
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It looks like Pikachu's take on traditional Japanese hair ornaments. You can tell it's female because the tail tip is rounded with a notch in the middle, making it look like a heart (see 3:02-3:13 in this video). The flowers make it more obvious to non-fans. Without them it's harder to tell, though they mirrored the tail. See also spiky-eared Pichu.