How to Sneak in a Pokemon Game

All items that you get in the game can transfer over. It's not one of these limited play demos. Not at all. After your tenth run is the last time that you get items. I did notice and I don't know what this actually means. There was a point where I was running through the tall grass and there was this dark shadow kind of jumping around in one of the parts of the grass. But when I got over to it had run away before I could get to it. My understanding is you have to do the sneaking thing. You have to like go over there because I was like, why can we sneak in this game? And then Justin F.T.W