They are usually there mixed with Donphan and Onix but during the months of April, August and December its winter in pokemmo. That means theres a few changes to some locations:
Vanillish @Icirrus City, Dark Grass, Unova
Beartic/Vanillite @Dragonspiral Tower, Unova
Cryogonal/Cubchoo @Twist Mountain - Ice room, Unova
Bibarel instead of Staravia @Valor Lakefront, Sinnoh
Jigglypuff/Swablu instead of Swellow @Route 115, Hoenn
Ursaring hordes @Victory Road are winter hibernating.
Shelmet hordes @Icirrus City are frozen during the winter.
Good luck o/