After sharing powers with his friends Shazam (Billy Batson) still seemed to have all his powers in the movie. Was this the case? Does this mean he can share his powers and create heroes without losing his own?
Well first of all he broke the staff so he can't create any more "Shazams".
In the comics, sharing his power did not diminish his abilities until Jerry Ordway’s Power of Shazam series.
However, based on the fact that he seemed to be the same after sharing his powers on screen, I think it didn't diminish his abilities.