From the Super Mario Wiki
The Style Sisters are a trio of clothing designer Lochladies from Super Mario Odyssey. They appear on the roof of the Water Plaza in the Lake Kingdom after Mario rescues Princess Peach. Unlike other Lochladies, they wear Bubblainian berets instead of the laurel wreaths that Lochladies typically wear. Each of them will give Mario a Power Moon if he is wearing a certain outfit. The pink one wants to see him in the Space Helmet and Space Suit, the silver one wants to see him in the Pirate Hat and Pirate Outfit, and the blue one wants to see him in the Cowboy Hat and Cowboy Outfit.
The Style Sisters also appear in other kingdoms. In the Wooded Kingdom, they can be found standing near the entrance to the Secret Flower Field. In the Metro Kingdom, they can be seen sitting on the roof of a tall building in New Donk City Hall Plaza.