A thread on the Marvelettes got me thinking: are there any other Motown groups that
a) had multiple lead singers or
b) switched lead duties from one member to another

In the case of the Marvelettes, Gladys seemed to have taken most leads up until around 1964. After that, they were mostly Wanda.

As far as the Supremes, Flo only had one lead single; Diana took the rest until she left in 1970. A case might be made for the 70's Supremes around the time of the "Touch" album, when Mary started taking some leads, through the MSS lp.

Of course then there's the Temptations, who had several lead singers. But other than that, it seems like all the other groups were one lead, and the rest background?