Okay SuperGengarMan, there are some things to understand first!
Pokemon you see in the over-world right in front of your eyes will sit there for eternity until you interact with them.
Pokemon met in a wild encounter in the tall grass is exactly as the name suggests; random!
That being said, the answer to your question will be no, you will not be able to get the same Pokemon by staying in a spot soft resetting and be able to get the same exact Pokemon.
When a random encounter begins, the game will select a random Pokemon found in that route and bring it into battle. The game does not have wild encounter battles preset within grass. It's totally random!
You said that you wanted to try and sit in the same spot and get a shiny; even if you were able to get the same Pokemon every time, you'd still have the 1/8192 chance of encountering a shiny Pokemon being applied to the wild encounter.
So there you goo! It just doesn't work that way; unless its of course visible in the over-world, where you're able to soft reset as many kajillion times as you want (such as soft resetting for a good nature for event Pokemon given to you when received by the delivery dude).
- 02.03.2012 2:13a