It's possible that this could have housed an NPC who would check how big a certain Pokémon is due to the poster on the wall.

31.5 is an unused house map for Seven Island that lacks event data.31.1 is the room hidden behind boxes in the old lady's house on Seven Island.The one on 19 is where the Pikachu's Beach minigame was in Yellow, so it is possible that they wanted to remake it as well. 18.1, 27.0, and 29.0 are three identical unused houses without event data on Routes 6, 19, and 23 respectively.The misspelling of the word 'stereo' in the Driver Test from Ruby and Sapphire was fixed in the equivalent of FireRed and LeafGreen as well as of Emerald, being now correctly spelled in katakana (ステレオ) instead of hiragana (すてれお), and the entry itself was also moved to the bottom. To access it, patch 0x12f342 to 00 00 00 00 and 0x12f35c to 01 FF 09 08 in a Japanese FireRed v1.0 ROM to replace the New Game entry on the main menu with a call to Sound Check (this has the effect of running Sound Check after the title screen if there is no save file). At least Japanese FireRed v1.0 has the Sound Check like Ruby and Sapphire, except it was removed in localizations this time around.

Pokemon fire red us 1.0