Dusclops can, and it can do so quite well, as its body is actually hollow, which means it’s lighter than it looks. (Well, to be more accurate, it’s sixty-seven pounds, but still.)
Mimikyu, meanwhile … technically can but doesn’t. It’s a spirit like many other ghost-types, but the problem is that if it hovers and flies, it risks allowing others to view its true form beneath its disguise. Hence, it keeps itself as close to the ground as possible to avoid accidental unmaskings.
The Pokédex According to Bill 