It is included in the Pokétch when you first got it in Jubilife City.
get the Poke tech App Poke happyness
talk to a girl in the eterna city Pokemon center on 1F
u click and hold the Pokemon with ur stylus
If you mean the itemfinder, you get it from dawn or lukas on route 207.
from dawn ( choose right hand )
go to valor lakefront with all the houses and use rock climb down to a house go inside talk to the guy he gives you poketch app 15.PS. the app is coin toss
In the app store
Find poke app 8(berry searcher) by a girl on route 208.
$XBIT. PJ Bitago - App Tech
easy go to the department store in veilstone city, on the second floor on the left there is three people go to the person facing forward and she will give you the counter app (app: 11
u can download the app for it! if u go into apple store should be there!
You get a special poke tech app and It shows you. The one were the Pokemon look like they are floating, you just touch them with your stialis.