The number of motors a robot can have depends on various factors, including the robot's design, purpose, and the resources available. There is no fixed limit on the number of motors a robot can have in general, as it varies widely based on the specific application and requirements.
For example, small hobbyist robots may have only one or two motors for basic functions, while larger industrial robots can have multiple motors for each joint and axis to achieve complex movements and tasks. The number of motors is determined by the robot's intended functionality and the available power and control systems.
In some robotics competitions and applications, there may be specific rules and limitations on the number and types of motors that can be used. It's essential to check the competition or project guidelines to understand any motor restrictions that may apply.
More robot motor recommendations can be learned : Exoskeleton&Quadruped Robot