well.....i havent actually found the assistant yet but i hear that he/she is by the honey tree north west on route 207 buy the trainer tips.(blue sign) hope this helps.
You get the Poketch Dowsing Machine from Rowan's assistant on Route 207 after getting the Bicycle. This is on Pokemon Diamond and Pearl by the way...
you will get the experience share when you go into Eterna City, professor Rowans assistant gives it to you.
it's not in route 207 dawn gives it to you
In Pokemon Diamond and Pearl, Phanpy swarms on Route 207.
You need to travel south on Route 206 in Pokemon to get to Route 207. It connects with Oreburgh City and Mt. Coronet.
route 207
in sandgem cityin front of the rowans lab which is on Pokemon hospital's left
Between Route 207 and Route 208
You Go To Profesor Rowans Assistant on Route 207. Well someone i know said that the dowsing machine is somewhere in the Jubilife building. And professor Rowans Assistant isn't on route 207 so don't listen to this one^.
the proffesor's assistant gives it to you on route 207 As you enter route 207 from the north, the proffesor's assisant will approach you to pick a hand. It doesnt really matter which one you choose, because you'll get the contents of both either way. One holds a Vs. Seeker that will help you find trainers who are ready for a rematch and the other holds a Dowsing Machine.
he gives it to you in prof. rowans lab. for this you have to complete sinnoh pokedex(excluding event pokemon).