Eclipse Studios (www.es3d.com) has some motion sets that include boxing, tackling and a few other 2-character sets that look pretty sweet. If you search you can find some mocap in other formats that also have 2-character sets. In fact, I'm pretty sure I've seen a set for 3DS Max biped that actually includes a cat fight between two women. It's fairly easy to convert biped animation to Poser if you know someone who uses MotionBuilder and, in fact, there's a tutorial on the Autodesk forum that pretty much describes how to do it.