The color(stupid UK spellings with their U's
j/k) of the tetra determines who the bonus tetras and the points goto, but whether or not you score the tetra is another story. First off, being able to pick up the tetra across the field before your opponent is questionable if they go for it, so you may end up chasing them around. Secondly, depeding on the speed of your robot, if you do manage to pick it up, will you have enough time left in the 15 seconds to cap.
Also, my team has thought of defensive strategies that could apply by tracking the opponents tetra. With enough speed, especially if the vision tetra is not their sole purpose in the auto phase(say if they take time knocking off the hanging tetras), it MIGHT be possible to beat them to the tetra and push it around the field as to keep them from using it. If they beat you to it, because you are still following it around the field, you should be able to at least nudge up against their robot before they cap(because they are in possession of the green object you are following, you'd follow them), or while they are capping. And depending on the force of this "nudge"(or the number of nudges) you might be able to hold them up for long enough to not allow them to cap during the auto phase.