You might not believe it, but Ojamajo Doremi has one. And it is Robo-Doremi◊◊. While in the illusion of a comic book, Doremi/Dorie gets turned from a little dog inexplicably into a giant robot. She even fights giant space aliens and causes massive explosions. However, what makes it a crowning moment is when she imitates the time when the RX 78-GUNDAM stood for the first time, pretty much frame by frame. Finishes with a classic gaze into the sunset and narrator's commentary. Considering how the rest of the show is, it's pretty awesome. Anyone got a better crowning moment?
"Hey, when am I gonna change back?"
Doremi gets one in Sharp episode 47, when her determination to get back Hana-chan breaks her out of the FLAT 4's shield.
The entire second half of the Grand Finale, but especially Hana-chan threatening to get Doremi out of the Maho-dou by using magic, only to reveal it was a Batman-Gambit when she forces herself out: she was bluffing.
Leon's Establishing Character Moment during his focus episode had him single-handedly defeating an entire basketball team. Aiko gets one of her own during that episode by beating him every time he challenged her.
Onpu continuing to act as well as tell off Tooru even after she suffers an injury.
Pop passing her first witch apprentice test in Sharp and saving the other Ojamajos from a milk flood and becoming a Level 6 witch.