3Dsim, it is impossible to answer your question properly without more information.
It should be easy to screw 3 of those shields to a plank of wood and wire them up. Power wiring will be important since you obviously have a lot of high current motors.
If you only have small motors then the Adafruit motor shield is stackable.
Each motor on the monster moto requires 3 pins to control it. One of these must be a PWM pin. Plus 1 analog pin for current feedback if you need that feature. That is 15-20 pins. More than an UNO but you probably already know that.