I guess I didn't use the right term there, to better express it, I mean that he keeps refining the looks of certain characters as the series goes on, not that their looks change completely or anything. The obvious one I think is pitou, not just because of the ribbon that got damaged in the fight, but also her facial features change quit a bit, at first when he/she was born, he/she looked more like a male but as the series progressed, he/she started to look more like a female. Also youpi and Morel both changed quit a bit. In case of the king, he doesn't really change that much since his design was basically a homage to cell, so you can tell that togashi had decided a certain look for him from the start, but then again he's one of the characters that i think looks exactly the same in both the anime and the manga.