It depends on the airplane. Most light airplanes require some coordinated rudder input, especially when rolling into and out of a turn. Large airplanes that have spoilers as well as ailerons do not require rudder input. Gliders, with their long wings and resulting adverse yaw, need a LOT of rudder to start and stop the turn.
Some airplanes, notably the Douglas A-4 Skyhawk with its delta wing, turn well with rudder alone, especially at low airspeeds.