As a rule, Player Characters or (PC's) can't/shouldn't use the last 4 colors of a palette.
The last 4 colors get overwritten in Battle, and the character's colors get all messed up.
Notice how none of the PCs originally use the last 4 colors of their palette. So they can be used for NPCs on the Overworld Map, like Ultros and Siegfried normally are, but if you plan on making them PCs, you must rearrange the palettes so you don't use the last 4 colors.
The last 4 colors get overwritten in Battle, and the character's colors get all messed up.
Notice how none of the PCs originally use the last 4 colors of their palette. So they can be used for NPCs on the Overworld Map, like Ultros and Siegfried normally are, but if you plan on making them PCs, you must rearrange the palettes so you don't use the last 4 colors.
We are born, live, die and then do the same thing over again.