Johto has almost all of the same Pokemon as Kanto PLUS MORE, and I think the real impact to the new games came when they redid some of the aspects in the THIRD generations, I think that the first and second generation just set the tone. The first and second gen were supposed to be the only ones until there was a popular demand for it and Pokemon became so popular.
Within my lifetime, I've done a lot of walking. I started my journey walking on a little path called Route 1. Little did I know that walking down that route would lead me onwards to a road that went by the name of Victory. Just west of Victory Road, I walked up an entire mountain where atop stood a silent trainer who was one of the mightiest I had ever faced. I've walked, through sandstorms, across the hard desert of Hoenn. I've walked through pelting hail, across the snow covered terrains of Sinnoh. And now as I look back on all my travels I find myself walking across the Skyarrow Bridge of Unova. It took a lot of walking through tall grass patches to get where I am today...But it was worth the walk.