User blog comment:B214/Volume 22 spoilers/@comment-27083298-20161115021134/@comment-10330822-20161116082427

Except the teams are not all always 16 physical people, it would depend on the worth of the characters and their strength. If Dulio is the King, and his Brave Saints are worth 3 or 4 people worth of Pawns, which they probably are lets be honest, he could still fill up a team with only 8-9 people. Plus, don't forget, some teams don't even have all their pieces. Rias and Issei for examples aren't even using both their Rooks, and Issei isn't using 5 of his Pawns. So, its not like the odds are stacked against them. Plus, there's probably other Angels besides the Brave Saints and Seraphim that sealed themselves away that could join Dulio's team too. In fact, if I recall correctly, there were another 6 Seraphim besides the Four Great Seraphim that sealed themselves away, and other lower ranked Angels.