It's a Shoe-In

It's a Shoe-In (also called Spike Castle a Go-Go!) is the sixteenth e-Reader level of Super Mario Advance 4: Super Mario Bros. 3. This card was released in Series 2 in Japan. Its official difficulty rating is ★★★☆☆. It was originally exclusive to Japan, but it became available internationally when the game was released on the Wii U Virtual Console in 2016. The key art featured Lemmy Koopa.

Level synopsis
The level takes place in a castle-like area, with many spikes in the level, requiring the Goomba's Shoe for navigation. This level contains many Thwomps and Koopa Troopas, with three Advance Coins as well. At the start of the level, Mario lands on a floating Switch Block instantly, making navigation to the first Goomba's Shoe possible and providing access to the first Advance Coin. This level indicates that it is possible to defeat Thwomps with the Goomba's Shoe.

New level elements

 * ? Blocks containing Goomba's Shoes

Trivia

 * A fan-remade version of "It's a Shoe-in", created in Super Mario Maker, was featured as one of Nintendo's weekly course selections. Subscribers to the Nintendo Newsletter received a mail on October 24, 2015 that included these course selections, with the renewed "It's a Shoe-in" being one of them. The course was remade by an Australian user called Nigge, and it is named E-16: Castle à Go-Go!, after the course's unofficial English name prior to the Virtual Console release of Super Mario Advance 4. The level is designed in the vein of the NES Super Mario Bros. 3, and its ID is BC9E-0000-0082-FFF5.
 * A notable mechanical difference in Super Mario Maker is that when Shoe-wearing players jump on Thwomps, they stand on them just like platforms, rather than defeating them, unlike in Super Mario Advance 4.