when you have blizzard you can only get silvia gk and when you have firestorm you can get only nelly nelly is fire and can use some moves of axel and silvia has god hand and fireball knukle she also can have shin god hand.
Upper Route of Hakuren/Alpine Coach, S Rank - Otonachi Haruna/Celia Lower Route of Hakuren/Alpine Coach, S Rank - Kageno Jin/Jim
Upper Route of Ouhimara/Mary Times Coach, Clear - [(Firestorm) Raimon Natsumi/Nelly Raimon(Blizzard) Kino Aki/Silvia Woods], [(Blizzard) Gouenji Masato/Syon Blaze (Firestorm) Endou Kanon/Canon Evans], Somoeka Ryuugo/Kevin Dragonfly, Kurimatsu Teppei/Tod Ironside and Shourinji Ayumu/Timmy Sanders. S Rank - Kazemaru Ichirouta/Nathan Swift
The other two Dark Emperors can be obtained by doing ALL the other competition routes besides the Mr.Veteran ones, I do not know which one is unlocked by which, or what rank you need but I do know that Max and Steve are unlocked by doing the other competition routes.
Nelly (Firestorm only) is found on the Tower Platform (No Scout) Silvia (Blizzard only) is found in Mark's room (perhaps looking through "some things")(No Scout) Syon Blaze (Blizzard Only)/ Canon Evans (Firestorm Only) is found under the lamp post in the first screen in Hokkaido(No Scout) Kevin is found just below the river pitch(No Scout) Tod is found in Naniwa Land on the screen where the Ferris Wheel, below the red building on the right hand side(No Scout) Timmy is found in the middle of the Cloister Divinity Pitch(No Scout) Celia must be scouted Jim must be scouted Max must be scouted Steve must be scouted Reply to this if you need any more information and I will try to get it