The rule says:
Quick look at all of G4 (c)
Loaders are an exception to this rule. If a Team only has two Students and is unable to field a three-Student Drive Team, they may choose from one of the following options:
i) For a given Match, they may substitute in a Student from their Alliance Partner’s Team as a temporary Loader. They may do this in as many Matches as needed.
ii) For a given event, they may substitute in a Student from another Team to be their Loader for the duration of the event. This Student will effectively become a member of the new Team for that event, and cannot fill a role on the original Team (or on any other Teams) for the remainder of that event.
iii) There is no requirement for a Drive Team to have a Loader; if desired, they can play the Match with only two Drivers, and rely on their Alliance Partner’s Loader.
The GDC went out of their way to be explicit about this rule. They did not say “another Team at this event to be their Loader”.
The GDC is also clear about not sharing team members at the start of G4:
Each Team must include Drivers, Coder(s), Designer(s), and Builder(s); many also include notebooker(s). No Student may fulfill any of these roles for more than one VEX IQ Robotics Competition Team in a given competition season.
I bolded the team members, note that Loaders are not on that list. Had the GDC wanted Loaders to be included in that list, they would have made that addition to the rules.
Based on that, you may borrow the LOADER from the other team. They must only be your loader, they can not Drive, Code, Design, Build for your team while they are at the event.
Remember, I’m just an opinion on the forum, and while I do stay at Holiday Inn’s, you should check the Q&A to see if there has been an update.
(Quick rant while I’m here: I like this game to the point of the balls being thrown. I hate the loader, the loader position, loaders throwing balls, loaders running around with balls, teams being forced to have 3 members, etc. If you want to introduce “Human Players” can I suggest First Robotics Competitions? they love that stuff.
I’m not at all thrilled to have 4th-5th graders being allowed to run around the competition field like deranged squirrels moving nuts (balls) around and then tamping down that energy for the rest of the event so they are not running into people. I’m also not thrilled with airborne movement of the ball. While I appreciate the GDC keeping the cost of the balls low, the balls rapidly deconstruct at the hands of a 4th grader. (And actually at the hands of an 8th grader too). And while I do live at the cradle of civilization and home to Betsy Ross, sewing skills are in short supply around here to repair them. Remember, this is not Project Runway, it’s Rapid Relay.
Thanks for coming to my TED talk. )