This is in no way scientific and based solely from observations of what others are doing but I think this is a genus specific question as to whether or not it is even worth trying.
Excuse my spelling of genus names.
Chamaeleo, seem to be very territorial, don't bother.
Furcifur, seems to be possible with enough room and close observation but watch the male female mix and individual personality.
Trioceros, generally seems to work with only 1 male and lots of room if watched closely. Mellers seem to be the exception and do ok in large areas together. Of course allowances for individual personality.
Thy pygmy genus's both seem to do well in groups but still be very careful about keeping multiple males.
I'm not sure about caluma, kiniyoga, or the tiger chams I haven't read enough accounts. (I feel obliged to apologize for the genus spelling again here).
I don't know if there is any benefit to keeping chams together where possible. Common wisdom here says no, there is no benefit outside of pygmies. But I'm not sure this can be said with any kind of authority across the board for every other genus or species.
For Veileds the answer is no, don't do it.