Guake terminal with 256 colors?
256color, terminal, vte, xterm
Solution
Guake supports natively 256 colours. And this is the answer to your question ;)
For testing it, you can simply run this script.
Problem
Is it possible to make Guake terminal to use 256 colors instead of just 8? The only info that I found on the internet is this post https://bbs.archlinux.org/viewtopic.php?id=173707 but it didn't work.