For starters, I will say Poochyena has an okay design, obviously not one of the best, but it's not really bad either, and the typing of pure dark I am fine with. However, the cons outweigh the pros, as Poochyena has poor stats, poor abilities (i believe) & poor movepool. Generally for myself, Poochyena is something I'd never use in the games, but just my preferences for the early game route pokemon you get in Hoenn, Poochyena doesn't really stand out quite as much as most of the others you'll find.
Coming in at #130 on my ranking is: