You get it from Dawn(or brandon) at the end of cycling road
you talk 2 your rival and she/he gives you one
you have to use your itemfinder and pick it up somewhere in sinnoh.
When you encounter Dawn/Lucas on Route 207 they will give you the Dowse Machine App (replaces the Itemfinder App) which will auto install on your Pokeetch.
I'm sorry but itemfinder only finds items not Pokemon wish it would
Pokemon emerald
Just find the itemfinder press A and select 'use' then you're using it!
Simply press the A button in the direction the itemfinder is pointing to.
use the itemfinder
the proffesors assistant (dawn or lucas) gives it to you sometime in the game. i forgot where because my playing time is 70 hours. it is a poketch application
Use the itemfinder where Mr. Fuji was in the Pokemon Tower.
Use the itemfinder.
You should be able to receive an Itemfinder off one of Professor Oak's aides on Route 11. However, you need to have captured 30 Pokemon or more to receive it.