Dia's peerage:
Mutation Queen: Rimuru
Mutation Bishop: Testarosa
Other Bishop: Shuna
Knight: Guy and Hakurou
Rook: Carrera and Shion
Pawn: Diablo, Rain, Misery, Ultima, Benimaru, Souei and the rest unknown (Know that each one to consume a single Pawn Piece)
Sera's peerage:
Mutation Queen: Milim
Bishop: Aurora and ??
Knight: Zelda and Thalia
Rook: ??
Pawn: ??