User blog comment:WeissSchnee/Characters and Pieces/@comment-10380701-20140604050120

Team MAID chose the black rook pieces. They're known prominently for their specialty in brute force, similar to how a rook charges only straight forward. They're also rather infamous.

Team MANA chose the white queen piece (originally the white king and queen, but I've retconned that) since they're considerably more flexible as well as skilled and are among the above average students of Beacon.

Team SLMN chose the white pawn piece, because they have the greatest potential among the three teams. At the present time, they're already alfway through the "board" into becoming a better piece, which translates to them having very specialized skills compared to each other.