It's basically because of how it learned Dragon Rage.
Iris really didn't put much effort in training it to learn that attack. I know that there were those practice matches with
Scraggy, but it felt like it was done for more comedy relief than to actually help both Pokemon develop and get stronger. When
Axew used Dragon Rage for the first time, it felt more like it was because the plot said so, not because of any training Iris did with it. That's basically my problem with Axew's development. Its strength isn't the result of any training, but just because the writers apparently want to make Iris a stronger trainer without having her do much of anything to make that strength more believable to the audience.
Bookmarks