Iggy Koopa is the only koopa without a hotel. However, looking through the game's data reveals each hotel has an internal music, graphics and enemy data file labeled from L1 to L8. L6 is missing in its entirety, and the game jumps from Ludwig's to Wendy's hotel (L5 to L7).

You can extract sound and cutscene data from L6, but the hotel is left entirely blank. This points toward Iggy being planned to have a hotel of his own, opposed to only appearing in Bowser's hotel.
Contributed by Outofmind23