Congrats on your 1000th post, SharkD, and I'd second the idea of at least having one sprite for each mech-producer. Can anyone recommend a good Wings/Blender tutorial? If so, I could take a shot at the Bargol/Pixie problem.
For the record, how do the transforming mechs call the second sprite? Looking at the Cogan, it's a battroid with variable components, but only one sprite reference. If it were to have a sprite for its aerofighter form, how would that be called?