i dont know why they gave psychic the purple colour... i guess it's not normally associated with a colour so they needed a colour that isn't associated with an element...

i was thinking of going along the lines of mewtwo's original armour's colour, blue-grey and purple. But I think it needs a bright colour in there as well, not much of a bright colour but a bright colour (like the bahamut in the first post). I dont think white stands out on grey so I don't think i'd use that... besides, there'd be enough white showing on the visible organic parts.