This was a given, the order has always been Asuka > Ikaruga > Katsuragi > Yagyuu > Hibari. Always.
I think it all makes sense.
Asuka and Yumi are the leader type characters. Obviously the leaders fight.
Ikaruga and Murakumo are traditional Japanese types.
Katsuragi and Yozakura have similar weapons, Yozakura doesn't like jokes while Katsuragi always jokes around. This is similar to Katsuragi and Hikage's rivalry in the other games.
Yagyuu and Shiki are the prodigy types I think.
Hibari and Minori... well, that's obvious.
The next bunch will obviously be
Haruka and Miyabi because, again, leaders.
Yomi and Murasaki because they both seem like heavy weapon characters.
Hikage and Imu because they're both devoted to just carrying out their missions, albeit Imu for the sake of Miyabi.
Haruka and Ryoubi will be fun. The two sadists against each other. Haruka will have fun teasing Ryoubi for her lack of breasts.
Mirai and Ryouna will be great again. The masochist who loves flaunting her breasts against the loli with no breasts. Mirai being hotheaded will keep attacking verbally and physically whilst Ryouna will love it because she's an M.