Part of the reason Trueno's colorset is as popular as it's been is partly due to the fact that it had a variety of useful colors. You only really need to have two rows of basic colors, regular and transparent. A lot of the colors in the third and fourth row could be dropped due to not much of a difference.
Typically you have to keep in mind that the limited amount of colors means that you would have to strive for more variety instead of having shades of the same color. A regular shade of magenta, a slightly pastel magenta and a darker magenta are all functionally the same when it comes down to it.
