You've seen the trailer for Street Fighter X Tekken, you've seen the playable demo as well as multiple screenshots. What you haven't seen is Namco's version of the fighting crossover, Tekken X Street Fighter. It's still in the very early stages of development, so early that Ryu's character model had to borrow Paul's wardrobe. It's looking pretty good thus far.
Enjoy the trailer, courtesy of GameTrailers,