Any clarification yet on if two robots can be on one balancing stone at the end of the match and earn “balanced” points?
You should post rule questions on the FTC Forum for official answers.
That said, Section 1.5.4 only talks of it being a stone of your color.
That said, why the heck would someone do that?
The answer is in Definition section 1.4
"Balanced– The condition where a Robot is Completely Supported by a single Balancing Stone and no outer
edge of the Balancing Stone is Supported by the Playing Field Floor, Robot parts, or Game Elements. "
So, short of 2 robots climb on top of each other, I don’t see how it would work at all.
I believe your alliance partners robot would fall under the category of “robot parts” so you’d want to be entirely side by side on the balancing stone in such a way that neither of you are resting on each other or the field tiles.