In that part Dragonite was ready to fight so that part is not holding back.And she stopped to help the opponent's Pokemon instead of straight attacking it. Don't see how that isn't holding back.
However, there is a part in Happynite vs Angrynite when after Dragon Dive crash with Dragon Claw, Happynite is forced down to the ground and look afraid while Angrynite hovering in front. It is like Happynite bowing down to Angrynite. Clearly Happynite is in vulnerable state and Angrynite could have easily finish it but Iris hold back and did not say a comand. This one is clearly holding back.