We've seen a ton of Street Fighter X Tekken and can practically confirm that the game is coming along beautifully. Tekken X Street Fighter on the other hand has been kept under wraps and heavily guarded, but this no doubt relates to the game's progress (or lack thereof). SF X T will equip Tekken characters with maneuvers to dodge the signature projectiles of the Street Fighter characters, but how will the fireball dynamic fit into Tekken's 3D world? It's a baffling dilemma, don't you think? Producer Katsuhiro Harada agrees, and he's confessed that the team behind T X SF is still unsure about how they'll deal with it:

Obviously, the Street Fighter characters will have to have their fireballs. Ryu without a fireball just wouldn’t be…right. Obviously we’ll need it.  It could be used as something similar to keep your opponent in the place you want, or it could be some kind of a special move or powered-up version of their techniques. We’ve not decided on what route we want to take with this yet.

Having a solid understanding of Tekken's fighting system, I think the best approach would be to make the fireballs uber-strong and limit the use of them. Since Tekken uses a 3D plane, you could simply sidestep a Hadouken and they would become completely useless once everyone got the hang of them. So they could make them really wide and really fast, so that you could sidestep them but not easily. It'd be difficult because you'd need speed and the ability to read them, but if they are this strong then they should be severely limited yo about three per round or something like that. Either way, Tekken X Street Fighter has no solid release details but is expected on HD consoles next year.

[PlayStation Blog]