Can you be more specific? What is you weight range. Lightest to heaviest it would be? What motor specs? Tracks or wheels? Are you converting a existing toy?

Two wheels. Supporting about 10 lbs

Or can I just use a high 10kg/cm torque servo

Ln298 would work if.your using a gear reduction motor. Or bv motor controller dj sells. If your using "drag turning" like a tank does without gear reduction you will want a h bridge that supports 5a. I imagine with almost certainly a LN298 h bridge with a heatsink and fan should do fine unless your using.heavy tank treads. I myself for example got a 10a h bridge just in case I raise voltage to get more torque (which will draw more amps) so I have plenty of wiggle room without fear of over amping. My Omnibot normally weights 16 lbs and dj uses a 1.5 amp controller but I've added another 15 lbs to mine with all the electronics.

Servo , yea it will need to be modified for continuos rotation. There's servos like futuba MG995 that are an.excellent candidate. I.have mg645 hitek that are 130 oz in torque either should be plenty for your bot at 10 pounds. Then you wouldn't even need a h bridge. Just run directly from your 6v battery. DO NOT run a high torque servo from easy board it cannot handle the current. Only use ground and signal wire to control rotation. If my drive train wasn't strong enough that would be the first go to. With the size of my bot I would need one of these modified servos on every wheel. The cost is only about 14 dollars per servo though . So about 30 dollars for you to get a set. Don't run them over 6 volts though. Servos have zero cooling and could burn up. If you buy the ezb kit you might be able to use multiple modified servos dj has. For example if you.had 4 wheels run one modified servo on each wheel.

What do you mean by "Only use ground and signal to control rotation?"

How would you power the servo and complete the cuircut?

Can you maybe draw it out. I apologize, I am new to this, but eager to learn.

@chris , on a servo there are three wires , the red wire you connect directly to battery , the ground must be split , and it connects to both the ground on battery and ground pin on the servo out on ezb. The signal wire usually white remains unchanged. Basically your just using power from battery and getting signal from the board. The ground must also be connected to ezb ground pin for reference.