Can someone make one? How far can you improve the odds? How do you do that?
Here are a few links that might help:
Wow!! Amazingly fast! Thanks man!!
Holy GOD!!! Dexnav and shiny charm will be VERY fast!! Can I know what pokemon spawn for dexnav on routes??
If you have them registered in the PokeDex, they should show up when you click the Search in DexNav. Otherwise, check the Insurgence wiki for what Pokemon are found in each route.