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.
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.
route 203 (mass outbreak).
there is no mass outbreak girl in soulsilver or heartgold. That was in pearl diamond and platinum versions. in heart gold and sould silver the mass outbreak is found by listening to Professor Oak's Pokémon Talk on the Pokégear radio in HeartGold and SoulSilver.
You need to watch the TV for the Route that the outbreak takes place.
wait for a mass outbreak on route 207
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!
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!
if you wanna catch beldum it a mass outbreak on route 228
route 27 water surface mass outbreak
if you turn you pokegear onto the music setting and listen to prof. oak and Mary's talk show, they will mention breaking news about certain Pokemon mass outbreaks... the Pokemon that have a mass outbreak will be different every day but there is a chance to have an outbreak of ralts
Pokemon #83 is a Farfetch'd. If you want to get it, you need to go to route 221 with a mass outbreak.
if by 'swarm' you mean a mass outbreak, then turn on your pokegear to the radio and go to the prof. oak and Mary's talk show. here they wil mention breaking news of an outbreak of a random hard to find Pokemon. the Pokemon will be random and be different every day.