This game is not balanced at all. The ninjas are clearly overpowered and for some reason never nerfed. Half the cast sucks especially the grapplers. I think I will go back to soul calibur, the developers of that game seem to actually care about balance.
Compared to DOA4, the ninjas are far from "overpowered".
The truth is, you're lacking the fundamentals and matchup knowledge to overcome these so-called "overpowered" ninjas, and rather than take the time to diligently learn the matchup, you dictate the game is "unbalanced" because you can't find an easy way to work around your problems with them... either that, or you're trolling.
At the end of the day, a character is only as good as the players who put the time into learning them and working around their weaknesses. Depending on who you play, I'm sure there is someone out there who can help you here. Surely you came here for that purpose. If that wasn't your purpose, your venting was pointless spam. I want to believe your intention for making this topic is the former.
At any rate, don't be so quick to throw the towel.