Sorry I didn't think it was something that could be spoiled....
But I can tell you this game was made with the facts that they wanted to please the original players and add new stuff to make it worth their time.... Johto is harder so don't slack off thinking you only have Whitney's Milktank to worry about....
I can't really remember how difficult Johto was in the original, so it doesn't make much difference to me.
But I have to say, I don't remember that Miltank being the demon everyone claims it to be. Not easy, but not throw-your-gameboy-across-the-room-difficult either.