I know the topic's old, but anyone still playing ZX, can you give me some suggestions on how to beat Omega in hard mode with ZX? 
The boring/cheap/easy/whatever you want to name it way: Just stay away from Omega and use a Charged Shot from ZX, X, or PX. PX is the fastest way and the easiest way, but only if you can get the range at a good angle.
The fun way: Make sure your reaction time is fast enough for you to dodge his attacks and hit him with a Kuenzan or a Ganzanha (ZX Charged Shot). When he uses the Triple Slash, if you're behind him, then use your triple slash to show him up

btw the fun way was never the safe way.