This does not refer to the role-playing cards introduced around MKII, but this deals with the standard playing cards with MK character faces.

My roster would be:

Ace: Scorpion (the kombantant icon of MK)

King: Sub-Zero
Queen: Kitana
Jack: Kung Lao
Ten: Sonya
NIne: Ermac
Eight: Noob Siabot
Seven: Reptile
Six: Kano
Five: Baraka
Four: Mileena
Three: Goro
Two: Shao Kahn

Joker/Wild Card: Raiden