if they were fighting in a traditional style war type of fight, brown would easily win. not bc its fighting, bc its simply overpowering the others by merging with the leftovers the other colors left bc of such a vicerous fight they are having.
also it would turn into one massive megacolor by, like i said, colecting the remains of other colors.
(i hate brown as a color but it makes sense)
if i had to make it unfair, purple obviiii, its like a royalty color to whom other colors would be bellow it, so they cant fight purple