It's something that struck me as odd in the final episode of Season 1 - I guess after that I just accepted the premise and suspended disbelief. I don't know if the Cosmic MacGuffin can make any Transformer a Prime -- it may have no effect (or detrimental effect) on a Cybertronian who isn't designated to be a Prime. But I suppose it can transform any 'compatible' (designated?) TF into a Prime... ermm... a wizard did it?