suitable condition for what exactly, dont have any idea where you are going with this....
[edit]
well if you mean you want to check to see if the unit selected is owned by player 9, look under boolean Unit - Unit Selected By Player (Which unit, and player X)
It may look at bit complex but i'm sure you understand it
(if you want this as an ability, make a check for an ability being use, then run the trigger i made)