Still gets wrecked. I have this in between Vegeta vs Dodoria and Vegeta vs Base Zarbon in terms of difficulty. Piccolo is strong enough that he won't need to use ki against Gero, and will be too fast for Gero to catch. Gero won't last long.
Depends whether you take Piccolo's removal of his weights against Gero as a necessity or for assurance in his speed. If the latter, Piccolo likely still wins. If the former, Gero may be close enough to tag him and drain his energy.