Just go full 100% offensive. I personally did it with Scorpion. Jumping away and doing teleport punches in teh air seems to catch alot of p[eople by surprise.

If somebody picks Flash, deffinately be Scorpionand use Inner Fire, only like one of flashes attacks can counter that and people never use them. you can do great. challenge people who ahve really bad records.

hey there.
just to tease u a bit :)
got my flawless victory on my second fight online.
i stopped playing mk since mk4 on pc and i have bought a ps3 console last week. took flash cause there's no kabal (sadly) and after going a couple of combo challenges i went online. 1st guy i met he was a quite good but when you go all offensive and u link moves together nothing can stop you. i took him 7 wins in a row then i stopped to go back to learning combos.
i am sure u are way much better then me so go out there and punish them :)

I always come extremely close to getting it but they always manage to throw a little jab or something in there before I finish them.

So close to %100 trophies. NEED TO FINISH!!