Hm... That might work, I've been considering it but again, I'm worried if he'll be too crappy. I mean, counter based characters have been done before, however, they're usually some of the lesser characters in the game because you have to predict your opponent quite well. Well, I should probably give an explanation as far as the basic design plan for the game it's self.
The fighting game kind of has a basic structure.
Light Punch - (You don't punch too often in Tai Chi)
Hard Punch - (Again...)
Light Kick - (Again, you don't kick too often in Tai Chi)
Hard Kick - ("^^)
In order to block, you press backwards.
You can duck by pressing down.
The game involves doing quarter circles and such. (Hadouken motions,
shoryuken motions, basic things like that)
There are also overheads in the game (If someone blocks low, it's a way to hit them "High", as if you were jump kicking them). The terminology is a tad complex and such, but I hope you understand the basics.
So then, blocking is essential to pretty much every fighting game. Every character can do it except perhaps certain boss characters that would be too cheap if they could. But that's besides the point. Let me explain a bit about Tai Chi Quan
Tai Chi Quan is a martial arts that basically throws the opponent off balance and uses the enemy's strength against them. You have to be flexible and "soft" when doing Tai Chi Quan. You don't block in Tai Chi Quan, you more or less lead your opponent's "energy" in a different direction. When someone punches, you more or less, point your stomach at the opponent, grab their arm while they're moving their punch forward, (You must focus your eyes on the opponent too) move your body and arms to where you'd like to throw him, and release. Anyhow, I'm sure you get the picture from this...