I'm guessing they appeared later in the manga, but the twins in Anima Yell were great. They had simple yet alluring designs, and their energetic antics were funny. Maybe not part of the main cast, but should've appeared more.
Lance n' Masques was terrible, and if they showed away from Loli stuff, they should've focused more on the talking mare and the blonde titty monster, they were easily more entertaining than the rest of the cast, though the annoying shota being treated like a jobber was also entertaining.