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There are many big helicopters which seem to taxi just as good as any fixed wing aircraft, for example CH-47.
Do their landing gear wheels have power or they also taxi using thrust like their fixed wing counterparts?
If they do have power, are the taxi controls different from the standard controls?
The wheels do not have power - there is no propulsion system linked to the wheels, they just spin freely.
Taxiing is achieved by adding just enough collective so that the helicopter starts moving, but not enough to lift it off the ground. A little forward cyclic also help.
To slow down, the main wheels have brakes, like fixed-wing aircraft.
Helicopter wheels do not have power. Taxiing is accomplished by using the thrust from rotors- for example, in case of CH-47, with rotors at normal rpm, the helicopter will have some forward speed (5-6 kt) with controls at neutral and thrust control rod at ground detent. Steering is usually using pedals (some helicopters have hydraulic steering) and there are, of course brakes (which are used to control taxi using differential braking in some cases).
As you mentioned CH-47, it is interesting to know that there are different ways to taxi the helicopter under different conditions. For example, according to the operator's manual,
Taxiing with two aft gear on the Ground
... Displace the cyclic stick aft approximately 2 inches and increase the thrust till the forward landing gear is off the ground the helicopter begins to move. Maintain directional control with the directional pedals. Control taxi by adjusting the thrust control rod.
and
Taxiing with power steering
... After the helicopter has started to roll, the thrust control rod should be lowered to the ground detent. This amount of thrust and braking will maintain a moderate taxi speed. ... Turns are initiated by slowly rotating the control knob a small amount and then gradually increasing the knob rotation until the desired turn is reached.
There are separate procedures for hover taxiing and water taxiing, though they don't make use of wheels.
MI-17s have wheel capability, but only utilizing thrust. No other system used for taxing. It uses main rotor to taxi ahead and tail rotor to turn left and right. Pneumatic available for braking.
Helicopters using wheeled landing gear do not have a drivetrain providing power to the wheels, though they are equipped with brakes. The helicopter can taxi on them, similar to fixed wing aircraft, or they can hover taxi, as most helicopters do. The primary usefulness in wheeled landing gear is to make it easier to tow and maneuver for parking, hangar storage, etc, while the engines are shut down. Virtually all large helicopters use this kind of landing gear for these reasons.
