During a elementary IQ finals match at a tournament I was at, a team's battery went down. An adult coach proceeded to throw the team a fresh battery, in the middle of the match. Is this an illegal action in any way? Mainly referring to rules R12 or G2?
Coach Interaction During Match
First, this would not be considered an R12 violation. R12 is intended to prevent Teams from using additional Robot Batteries as counterweights or finding ways to double their available power. As noted in this Q&A, swapping out a battery mid-Match is not illegal, provided that it is done under a legal G17 / RSC5 interaction.
G2 is quoted below, with a portion bolded for emphasis:
<G2> VEX IQ is a student-centered program. Adults may assist Students in urgent situations, but adults should never work on or program a Robot without Students on that Team being present and actively participating. Students should be prepared to demonstrate an active understanding of their Robot’s construction and programming to judges or event staff.
Some amount of adult mentorship, teaching, and/or guidance is an expected and encouraged facet of the VEX IQ Challenge. No one is born an expert in robotics! However, obstacles should always be viewed as teaching opportunities, not tasks for an adult to solve without Students present and actively participating. Violation of this rule could be considered a violation of <G1> and/or the REC Foundation Code of Conduct.
In the specific scenario that you have described, this would likely be considered an "urgent situation", especially because the Students were the ones who identified the root cause of the problem and physically changed the battery ("worked on the the Robot") mid-Match.
Therefore, the act of a Team receiving a spare battery mid-Match is not illegal in itself.
With that being said, we definitely do not want adults to get into the habit of throwing batteries at Students! This could be deemed an S1, G1, G2, or Code of Conduct violation, depending on the manner in which it is handled in the context of the event. It would be impossible for us to provide a blanket response that would encompass all possible hypothetical interactions.