Using Multiple Kinds Of Motors

[DonRotolo]

First, what ChrisIsMe said.
Then, what BJC said.

The issue is defining the problem. Do you really want all possible energy being put into the drivetrain? Is it needed and, if so, to what end? Can the drivetrain do something useful(er) with all that power?

Way back before small electric motors were available, workshops all worked off one single power source - a water wheel, steam engine, gasoline engine or (large) electric motor - with a shaft that ran the length of the shop. Each machine had a long leather belt that took power from the shop shaft (with a clutch that could be disengaged when desired). In this way, all of the power was available to any machine that needed it, or a fraction was available to every machine in the shop.

What if you built a robot that shared ALL the mechanical power like that?