It seems the reasoning for this is that the game believes those trainers have already been defeated. Upon trying to force a battle by interacting with them, they merely said "I've lost..." or some variation of such. The Gauntlet Mode is what I consider the most reliable way to level up your pokemon in preparation for the Final Cave, so to see that it's broken in such a way is pretty disappointing. Please figure out the issue and solve it, Savordez!