Rain a sub boss?

[The 7th Number]

In the 2 full totem poles i saw when you do the 1 player mode Rain was always the 3rd to last. Now this could be a coincidence because i have also noticed that Fujin was the first opponent 2 times too. Here is my research from videos and pics. im also not sure if these are random or they depend on who you are.

- as created player
Blaze
Goro
Rain
Shao Kahn
jerek
Stryker
Shinnock
kintaro

- as Sareena
Blaze
Reiko
Rain
Kai
Sareena
goro
Sheeva
Fujin

- as Sektor
bottom 4
Sareena
Stryker
Sheeva
Fujin

- As Goro
bottom 3
Stryker
Shinnock
Kintaro