Forgive me if this is a commonly dismissed question or if no one knows yet, but this is kind of a deciding factor to which I might consider this game or not. I find Pokémon's aesthetic and overall charm to be great but it's just way to easy for me to enjoy anymore.
Also by proper, I mean that Black/White 2's method of unlocking difficulty modes was not at all the way to go.
When other games do it, you unlock it after beating the game, then you get to keep it unlocked no matter what. In this case, if you deleted your pokemon save, you would loose challenge mode, making it basically pointless if you wanted to use it through the story. --- http://s7.zetaboards.com/Burnin_Rubber/index/
It should have a difficulty level you select at the start of the game.
Big yes to this, it's pretty stupid you had to unlock it and that it only existed in one game, and tht you had to trade the key thing over to another game, but the dumb thing is that when you erase your save file, you have to unlock the thing all over again.