Such an ultimate format would pretty much be impossible to do. It would most likely be easier and take less space to create a program that would output the map straight from the rom using the correct tiles, palettes and whatever internal transformations needed and then add all the sprites wanted.
I remember reading about a guy who was trying to do something similar but for a video format for NES games that would thus have perfect image clarity and would require a much smaller bit rate than most existing video format.
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"With the first link, the chain is forged. The first speech censored, the first thought forbidden, the first freedom denied, chains us all irrevocably." [...] The first time any man's freedom is trodden on, we're all damaged. - Captain Jean-Luc Picard
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