Swarms

Go to Pewter city then talk to this guy. He will say that there will be a rare pokemon in a certain route.

It lasts for 10 minutes so be quick.

The pokemons that can have swarms are

-Treecko

-Mudkip

-Torchic

-Oshawott

-Buneary

-Nosepass

-Wailmer

-Lotad

-Beldum???

-Lickitung

-Jynx

-Shinx

-Ralts

-Starly

-Sneasel

-Slakoth

-Scraggy

-Carvanha

-Croagunk

-Mareep

-Larvesta

-Shaymin (SUPER RARE)

-