Its wings are too tiny to allow it to fly. As the time approaches for it to evolve, it discards the bones it was wearing.
– Pokemon Black Pokedex
Vullaby is the Diapered Pokemon, and indeed the half-egg shell it’s wearing looks like a diaper. Its facial expression looks like a disgruntled baby, haha. Its type of Dark/Flying is only shared with the Murkrow family. It evolves into Mandibuzz at a rather high level, level 54.
Stat-wise, its HP, Defense and Sp Defense are its highest stats. Maybe because it evolves so late, it can learn moves by level-up up to level 64. It’s one of the few Pokemon to learn Defog by level-up.