So yes you absolutely /can/ submit a model trained on your own private data set even if what you submit is a model code that will be re-trained. Even if "the training set" is different to the provided - you still have that scraped data so you can slice it up with the provided training set so that any selected training set does well against the rest. Now the overfit you've just carefully engineered should win against the honest models unless you suck, right? It's kind of risible that they had to go further and hard code certain results, don't you think? Perhaps if they still couldn't win with scraped, illegal additional data then everyone else had illegal data too? Perhaps Kaggle is not a good indicator of how good ML techniques are in practise? Perhaps Kaggle systematically overstates ML effectiveness due to this kind of uncaught cheating in many of their competitions? I bet kaggle won't look too hard at that.