Well hello there CLOUD!
Since you’re in this room with troopers only two times (unless I missed something) and in the first instance Zack still has his purple 2nd class uniform which he doesn’t have in Cloud’s memory
So this was probably after Zack outsquated him and that’s why Cloud is on the ground because he simply can’t stand anymore. Which makes Zack’s super serious face really hilarious. “Squats are serious bsns my friend!”
So I guess Cloud and Zack first met at a squat battle.