#123 - Iggy's Lost Hotel

In Hotel Mario, every Koopaling has its own hotel except for Iggy Koopa, as he shares hotel with Bowser. In fact, there's not even any data of that hotel, and the game skips from Level 5 to Level 7. However, there's empty data of an unused Iggy cutscene.

SOURCE: https://tcrf.net/Hotel_Mario#Missing_Level