There are many elements to being a good stacker. My team is still far from a good stacker (although we were closer then any other team at cleveland
)
1) you must have bins to stack with, so either you or your partner must have a good autonomous mode.
2) you must have some way to get those bins upright, and quickly
3) you must have some way to pick up boxes that are not lined up perfectly with your robot (most internal stackers have this problem)
4) you must be able to accurately place the box on another (most arms have this problem)
5) you must be able to protect your stack for the majority of the match.
6) you must have the traction and driver skill to do all this while being harassed.
There are probably a lot more, too. Our robot is deficient in several of those. The best video that I have seen of our robot stacking in real competition conditions is qf1m2 from soap (10mb)
http://www.soap108.com/2003/movies/oh/oh_qf1m2.asf also good to note that we lost that match. In fact we lost most of the matches where we stacked. So just because you can stack doesn't mean that you will do well or seed high.
I will be very interested to see how you guys do at competition.