Hi, in pokemon black, Mising.No does not crash the game, but it can't learn any moves so i'll struggle to death.
Even if you hack Missing.No in, most software will not recognize it, so it will default to Bulbasaur or crash.
Plus, Poketransfer DOES NOT allow Missing.No to be transfered to other generations, as Missing.No is not recognised as a real pokemon.
Hope i was helpfull :)