A feature that was introduced in Past games is the implementation of Swarms. These are where Pokémon in certain routes have their appearence Percentage raised so that they are more common.

In Diamond & Pearl however, after you get the National Pokédex, if you go to your Other Rival's house in Sandgem Town and talk to their sister, they will tell you that there is an increase of Pokémon in a certain Route or area

If you go to the route or area that the girl states, within one or two wild Pokémon battles you will find the Pokémon at the same level as the other Pokémon.

The Pokémon and Route change every day and all of the Pokémon that you find and their evolutions are not obtainable by any other means in Diamond & Pearl so be sure to capture them while you have the chance.

Below are all the Swarming Pokémon and the routes/areas they swarm in:

Swarming Pokémon

Location Nat No. Pic Name Type 1 Type 2
Route 201 #084 Doduo
Route 202 #263 Zigzagoon  
Route 203 #104 Cubone  
Route 206 #299 Nosepass  
Route 207 #231 Phanpy  
Route 208 #206 Dunsparce  
Route 209 #209 Snubbull  
Route 213 #359 Absol  
Route 214 #325 Spoink  
Route 215 #096 Drowzee  
Route 216 #225 Delibird
Route 217 #220 Swinub
Route 218 #100 Voltorb  
Route 221 #083 Farfetch'd
Route 222 #300 Skitty  
Route 224 #177 Natu
Route 225 #296 Makuhita  
Route 226 #098 Krabby  
Route 227 #327 Spinda  
Route 228 #374 Beldum
Route 229 #016 Pidgey
Route 230 #222 Corsola
Lake Verity #283 Surskit
Lake Acuity #238 Smoochum
Lake Valor #108 Lickitung  
Fuego Ironworks #081 Magnemite
Valley Windworks #309 Electrike  
Eterna Forest #287 Slakoth