Well, Blue only need Greens for weapons. It'd be a great reason to rely on the team if you seriously are unable to hit back. But yellow could be interesting, but would require one really good explanation. But yes, more lunatics there

Star Saphires, though, not much in the way there. And with Indigo you could totally have all sorts of effects. Green is certainly the most straightforward, though.

EDIT: Not that I'm arguing, master, just thinking out loud-ish