I really like that the slots are getting into some better specifics regarding character powers.
Two things about slot 3. First, isn't Bumlebee way more powerful than anyone else listed there? He may not be a good example of a low powered robot. Second, are machines that infect other machines allowed? I'd hate to see a character chosen who wins every match with "Character A controls Character B's mechanical brain and forces it to self-destruct lawlz." Would get annoying.
The characters have to be self contained and can not replicate or take over the other machine. Example T-X could be used but for the season purpose, she cant simply take control of the other robotic character. There are many characters to choose from in this category. Bumblebee would be high powered but there are plenty others that could be just as dangerous. A normal (low tier) transformer I would say would be the max on power level though.