i reaally want it its my fav Pokemon. oh yea, I forgot...IT'S ON POKEDEX 3D!!!
If you want Deoxys (all formes) on your Pokedex 3D:
Sorry, that is impossible, as the Pokedex 3D is the Regional dex for Unova; Deoxys is not part of that.
If you want Deoxys on the Pokedex 3D Pro:
Yup; you have it by default. No need to scan.