Up until now, the anime always had the Pokemon glow when they evolve, covering up the transformation. However, with Sun and Moon, they showed the first evolution of this era and I can say two things about it.
1. It's with a female Pokemon (Bounsweet to Steenee), meaning I can talk about it on this website.
2. They actually showed the evolution! Amusingly, it comes off like a Magical Girl transformation.
See for yourself.