Yep. It is a Swarm Pokemon. It can be caught on Route 1 with a Swarm. Level 2. http://pokemondb.net/pokebase/18652/what-does-swarm-mean
A Poochyena can be obtainable -By Trading a Mightyena and Breeding via the GTS or a Local Trade. -Trading one through the GTS or locally -Transfering one from Emerald to DPP via Pal Park and trading it to HH/SS