Oh, right.

It might help to ask your party mates what they are running, and then building something that can fill the empty niches.

Other than that, its ultimately your character. The flexibility of M&M means that you can make him pretty much whatever you want. Especially since Nanotech as a descriptor is sufficiently broad to enact almost any effect. , So visualize for yourself what you really want him to do, what do you think would be cool, and work from there.

Or if you want someone who can really pull all sorts of crazy stuff on the fly, try taking Shapeshift. Just try not to break the GM.