Well... People who've played Dissidia for 50+ hours come and faces me thinking they stand a chance in Adhoc-Party for the PS3. I tell you that 50-200 hours is not that much if you haven't played online before or played fairly against the computer and learned all mechanics. Those poor suckers use cheap tactics that is used against the A.I towards real players. They don't know how I'll counter and attack freely as if there is no punishment for it.
Learn all abilities for every character, learn how their abilities can be used, combos, guard breakers, bravery-hp chains, mind playing, trapping, whatever it may be. The mechanics for everything is important to know since they are the biggest first thing to learn fully, after that you can focus on combo's, more in-depth builds, tactics, mindplay, all because you know the mechanics. Of course you'll do all that while you are learning mechanics but you can do it alot easier when you know them.
Do you have a PS3?