There's a limit to what judges can do, but this doesn't mean we won't try to enforce the rules.
As an example for what regards assets: if the submitter has a social media presence, a YouTube account and/or previous games where the model/sprite/music was used, we might find out rather easily. AI-generated art is also (still) pretty easy to spot.
For what regards AI coding: If e.g. the submitter is a staunch online AI advocate and has devlogs about vibe coding other games, we would double check them before allowing the game to be graded.
We can't read minds but we can make reasonable efforts to ensure a fair competition. This doesn't prevent people from cheating and we are aware of it, but it doesn't mean we don't have to try.
Of course we expect most participants to play fair, since there is no money involved nor a prize. If a breach is discovered retroactively, the game will be removed from the jam and publicly retracted. The indie developer community around fighting games is very small: being exposed for cheating in a jam where most of these devs are taking part in would put the transgressor in a bad position, career-wise.