Location: Inverted Pyramid, Sand Kingdom
Phase 1: Harriet will throw bombs that explode into hairpins. Dodge these. She will then throw a large spiked ball. Capture the spiked ball with Cappy and throw it back at her. It will hit her and knock her down.
Phase 2: She'll fly around, dropping more bombs and spiked balls. The strategy is the same: dodge, capture a spiked ball, and throw it back. She might also try to stomp on you; dodge this as well.
Phase 3: Faster attacks and more projectiles. Continue dodging and using the captured spiked balls. Three hits will defeat her. The key is to quickly capture the spiked ball and aim it accurately.
Reward: Multi Moon