It's not hard, but actually medium difficulty, which is a standard game setting. And yea, I've won it
As for the "secrets", you don't need any. You just need to know CPU patterns. When you'll know them, the game will be easy for you.
In the beginning, try to avoid close in fighting, 'cause the opponent will throw you in most cases. Instead, use timed/early jump kicks and precise sweeps a lot. You can sweep multiple times, but they have to hit the feet of the opponent at your fullest range or else you most probably will be thrown. You can also try the jump back trick. You have to jump backwards from the opponent and when they follow, you can hit them with a roundhouse, an uppercut or punch them while their falling and continue the combo.

I beat it, but only once, I was stuck on Kintaro and Shao Kahn for a long time though, I beat it with Liu Kang and YES I am talking about MK2 the unlockable game in Shaolin Monks and NOT Shaolin Monks itself