Could be like a sub-group theme, that allows collectors to display them together like a set.
One thing I'd like to see in a series is several intermittent toys released over a year in a similar theme or colour, but not revealed in the show like a year later that they have a common link or bond, or come together as a sub-group of warriors, reguardless of allegiance. Then again, it'd be a toy scalpers paradise, as heaps of collectors would suddenly be hunting down several toys no longer available at retail.