I understand the groups and 4 bytes per palette and how to find them but what i was really trying to find out is if they are stored one after another in the rom with no other data in between.
To expand a bit... a game will usually have any number of palette groups. For example, SMB3 might have one group that is dedicated for background palettes for different levels in the game.
Each group will store its entries sequentially. So if SMB3 has 1 palette for each level, you will probably see a big table of palettes, with the first 4 entries being the palette for 1-1, the next 4 being for 1-2, etc.
Other groups (like enemies) will be stored in a separate area in the ROM, but likely in the same fashion.
Note that my level example was over simplistic to give the idea. Likely there is a layer of indirection. For example... each level might only have a single byte to indicate a "palette ID" for it to use. Then the palettes which correspond to each ID will be in the big table. This saves space because it allows multiple levels to use the same palette information by giving them the same 1 byte ID, rather than the same 4+ byte palette.
Palette tables are usually pretty easy to spot, as they often have the same value (usually 0F) every 4 bytes, and no bytes are higher than 3F. Here's an example from Final Fantasy:http://i.imgur.com/oKzSXiC.png
It's pretty easy to see the pattern of a palette table starting at offset 0x2010 here.
In FF1's case, each row of bytes here is the palette for 1 map in the game. So the first row is for the first town, the next row is for the next town, etc. Enemy palettes, character palettes, etc are all stored in very different areas.
Knowing that the map palettes for the first town in FF1 are "1A 28 18", I would have found this very easily with a Ctrl+F. And then I would see that the rest of the bytes in this area all have this pattern, so I would quickly identify it as a palette table.
One thing i dont get is the grayscale palette you mentioned, care to explain plz?
Forget about it. It was a poor example to illustrate how a palette looks. The above visual should be easier to understand.
Datacrystal has some of the palettes outlined already. Dunno if you've seen it:http://datacrystal.romhacking.net/wiki/Super_Mario_Bros._3:ROM_map