Like I said earlier, I love Generation V. One thing I love is how it amplified the brilliance of ghost-type pokemon. With only a family or so introduced each generation, the talent pool in the Ghost department is slim pickings. Then along came Unova and with it awesome Ghost pokemon, like Yamask.
I really like Yamask because it is easy to draw and is the only ghost pokemon to be an actual ghost. It really is a dead person's spirit. Its pokedex entry is a bit gloomy I must add and has been described as the most depressing pokedex entry since Cubone. Yamask's evolution may be leaning towards daft, but Yamask is a respectable pokemon, that I for one cannot get enough of. The face mask it carries is creative, unique and a little creepy, like any ghost-type pokemon should be. It's name is a bit on the nose, but so what. 156 pokemons names to come up with is hard and some of the Gen V names are really clever.
As I bid you a due, I'll conclude on Yamask's ability, it is a bit like a zombie virus but like a slow zombie does absolutely nothing.