Except it was her fault. Had she understood him all of that would have never happened.
Had she allowed him to give up on the battle like he wanted? Fostering in the process Doryuuzu's feeling of weakness and inadequacy? That would have really been her fault. That would have portrayed her in a negative light, that would have then caused a problem, like Doryuuzu having no confidence and not wanting to battle. That would have forced Iris to take a look at herself and realize she should have believe in him in the first place, allowing both her and Doryuuzu to grow alongside one another... In short, that would have been developement. Instead we have 100% of the problem solely on Doryuuzu's shoulder, Iris being shown as capable, skillful, knowledgeable, caring, encouraging, but misunderstood by her pokémon, then she apologizes for doing nothing wrong, prompting her pokémon to realize she was right all along. In short, what we had was uninteresting and held no developement for Iris.