It is determined by the in game television it will be either Seedot or Surskit.
sentret
there has to be a pokemon outbreak for it to work, s/he is in route 2
You need to watch the TV for the Route that the outbreak takes place.
route 203 (mass outbreak).
The 'mass outbreak' is a swarm of Pokemon that you would not normally find anywhere else, and are at extremely high frequency rates. You can listen to Professor Oak's talk show for what the mass outbreak of Pokemon is and on what route it is on.
wait for a mass outbreak on route 207
When the electric boards say there is an outbreak of Pokemon in route 10 that is where you can get one
Seedot is a rare Pokemon that normally can't be found unless there is an outbreak of them on certain route so how do you know when an outbreak occurs? Find a TV in a house and check it every day until Pokemon news airs wait until they tell you there is an outbreak of seedot on route whatever go there to catch seedot.
A "Mass Outbreak" is when many Pokemon show up in a area where they usually not found. Every day go to Dawn's House in Sandgem Town and talk to her little sister, she will tell you what Pokemon and what route for the mass outbreak! Hope This Helps!
It is exactly where you described it. It's on route 9. If you mean specifically how to get the Pokemon, you need to go into a grassy area, cave, or other place where wild Pokemon appear on that route to find the swarm Pokemon.
Pokemon #83 is a Farfetch'd. If you want to get it, you need to go to route 221 with a mass outbreak.
if you wanna catch beldum it a mass outbreak on route 228