I'd like to get 100%... as someone else said, I'm not into fighting games usually but mortal kombat is an exception. I've always loved it over street fighter ever sine mk2.
I just got the "finish arcade on expert no continues" achievement with Liu kang!
Some boss tips for people going for this one...
Kintaro: stay as far away from him as possible, and he will either taunt (throw a projectile at him) or do his teleport stomp... When he does, side step/side jump and then combo him as much as possible, then repeat
Goro: stay in the air. His specials are all stomps, so as long as ur jumping and kicking, it'll be hard for him to get you... Try jumping over him when close in case he grabs you, then hit him from the back.
Shao kahn: people like to stay away from him and use projectiles, but on expert he closes the gap too quickly, so stay close to him, and try to jump over him and do combos from the back as he goes to swing his hammer, it usually leaves a large opening for you to strike. Remember STAY CLOSE, and as he gets up off the ground jump over him again, and repeat, he usually goes for the upwards hammer strike when your close and he's recovering. I got flawless victory on expert like this (took 6-7 arcade ladders on expert till I figured out this strategy)
Hope this helps.