Quoted By:
Having seen the episode a few times now, don't kill me, but I feel this to be true.
Even if Serena had not failed earlier, she would not have won. She has no idea what Performing is like. And she couldn't compensate with confidence, like Shauna did. It was clear Shauna, while also this being her first Tripokalon, had the vision and foresight to face her destiny. Serena, when she's looking on later, realizes what it's all about. It's not about being cute. It's about performing. Her costume for Fennekin focused too much on cute. She didn't pay attention to functional. Or even symbolic and meaningful, like the Heliosk sun disc. If she HAD made it, she would have been utterly crushed in the performance round.
For all you Amour fans, it's better for your delicate feels that she failed now. To be honest, I felt that room for real character development can't really take place past this, since she's already 'done' it. A shame, but hey, adorable it is. Unless they go for propping her up with a victory or two, or even an outright winning the Key once, followed by falling flat on her face performance wise.
As it is, right now both May and Dawn could smash her flat, even without their considerable experience. Both had more of a sense of execution during their first rounds.