I learned rolling circles with my avistar years ago. Giving rudder command on a trainer that dosent have any type of mixiing through the transmitter (I had a basic 4channel radio with no type of mixers, not even dual rates) will give an opposing roll input so rudder had to left alone. Even still I made the roller look perfect by timing when and how much elevator was given to keep the nose from jumping up and down. When the plane was further out it look better but If I had to slow it down then the bouncing would be more pronounced.
Also in a truly smooth 1 or 2 two roll circle you will be adding two inputs at all times. As soon as you start to let off the elevator you should already be adding in the rudder and so on. Quique rollers are so smooth that he can stop the roller at any time and start again without even loosin altitude the whole time.