You know when he can learn fly. But, is that great? Because it's useful for cover grass Pokemons.
It's not to bad it does cover some weaknesses like you mentioned and most Pokemon that can learn fly would have it in their move sets competitively. To be honest though, for in-game, its fine, look at the "what's a good move set for golurk" on this site for a better competitive move set. It depends on what you want\need it for