How about a deep green and purple combination, like the incredible hulk but perhaps darker. With a bit of weathering I think it could work really well.
Although those fliers would make me paint them as hobgoblins.
Of course, there's no reason you can't have uniform colour schemes per unit in an army. I would probably paint all the dudes on hoverboards as hobgoblins and all the footmen in hulk colours. If you have insignias etc, they'll tie together nicely anyway.