GameXplain has released a video showcasing the abilities of the new item in New Super Mario Bros. Wii U Deluxe game.
The Super Crown power-up is an exclusive to this port of the game. It allows for Toadette to transform in Peachette along with a few more advantages over other power-ups.
Peachette has more control in the air than the squirrel suit, automatically jumps after falling into a pit, and provides maneuverability in water similar to the penguin suit.
The full video explaining the difference between this new power-up and the older ones is below.