There are three unused palette sets, two of them may have been used for testing purposes.
Both PAL_01 and PAL_23 entrees exist. It is unclear why the black and white palette was used. Located at 0x1F2AB. Game Genie codes EA9-23E-6EE + ABA-78E-7F7 + 72A-79E-91A will load the unused palette, IDsAB, BB.