yes, yes you can.
The Poke Radar is not available in Pokemon Sapphire. The Poke Radar is an item exclusive to Pokemon Diamond, Pearl, Platinum, X and Y.
complete the sinnoh pokedex
In Pokemon Pearl, Ditto can be found in route 218 using the Poke Radar.
In Pokemon Pearl you can find Tauros in Routes 209 and 210 using the Poke Radar. You can get the Poke Radar after seeing every Pokemon in the Sinnoh Pokedex and getting the National Pokedex.
use the poke radar at the trophy garden
Route 228(Poke Radar, Rare)
route 224(use poke radar)
you can get him on route 211 with a poke radar
go to fuego ironworks with poke radar
in route 224 "use poke radar"
Route 228 (use poke radar).
use poke radar in grass near jubilife
Trade with other people with it or Poke Radar (its a rare pokemon.)
After you finish your Pokedex, talk to Professor Rowan and Professor Oak and they will give you the National dex and the Poke radar.
To get a shiny Pokemon try using the poke radar
use poke radar at certain routes
use the poke radar in route 212.
use a poke 'radar in route '218'
Rt. 206(Poke Radar, rare)
Use Poke Radar on Route 229.
If you use the Poke Radar you will have a chance of getting a shiny Pokemon. But the actual Pokemon will not USUALLY change by using the Poke Radar.