Just discovered this thread so here goes: Red Velvet one of the best Kpop girl groups out there. Great songs and MVs. Difficult to say what genre of Kpop they are except: the Velvet songs are smooth RnB types and the Red songs are Upbeat, often featuring cute; but sinister or quirky themes. Even trippy.
https://www.youtube.com/watch?v=J_CFBjAyPWE
The Velvet side
https://www.youtube.com/watch?v=YBnGBb1wg98
The Red Side