I don't know why it had escaped my attention for the umpteen times I re-watched it but in episodes 108-109, Judai would have legitimately lost to Austin O'Brien. There was no asspull potential remaining because at the final turn, Judai had just 1 set card (Elemental Mirage) and 1 card in his hand (Elemental HERO Wildman). There were no cards that could be activated from Judai's graveyard.
If O'Brien had activated his facedown Volcanic Force, it would have special summoned Volcanic Devil and forced Judai to attack it with Wildman; winning him the duel. The plot would have gone in a slightly different direction, and he would have become the third person to beat Judai. But he didn't do it and threw the game on Professor Cobra's orders.
Also, throughout that duel O'Brien was able to perfectly predict every move Judai makes (except Contact Out, which impressed O'Brien so much that he temporarily abandoned his mission and tried to win).
I liked the character before, but I like him even more now. Was he the strongest among the five academy champions? I think he was. Only Amon could have given him real competition. I don't think the rest would have. Wish they had shown more duels in between themselves. He even drew against Haou who had Super Polymerization and the formidable (at that point) Evil Heroes.
Sort of trivial, but what do you think?