Answering the question of your thread, below is how I think where the the speculation of these types came from. And above all, as blaze boy said, they're wishes of fans.
Fairy - Fairy is speculated probably when they designed Celebi. Celebi is arguably a fairy, but the nearer element to type her in that generation besides Grass was Psychic. Maybe they'll switch her to Grass/Fairy type or not. Along Celebi we have very few Pokemons that are related to fairies, the only are in Clefairy's line. Although the Fairy egg group is large, most of the Pokemons in there doesn’t have the apperance based on fairies, as Pikachu and Granbull, for example.
Light - The speculation on light came out since generation II when they created the dark type. Light is opposed to dark. Fans expect the light type since dark came out, however, due the real meaning of dark in Japan, light type isn't likely to be created. Also, if there were a nice moment to introduce the light type, that was Gen because we got the black and the white dragon.
Sound - The idea of a sound type is presumably supported since Generation III with the design of Loudred's line which got all the moves based on sound. Also, on generation IV we got Chatot which is strongly related to sound moves. We have already an ability that is grants to the user immunity to sound-based moves, why now make them sound type and make the ability grants immunity to sound type moves?
Cosmo - The cosmo/alien/comics or type is speculated since Generation III when non-Earth native Pokemons were designed, like Jirachi, Deoxys and Metagross' line. I see also Mew as a Pokemon from the outer space due its alien-apperance.
Virus - I never read the speculation about this type, so I cannot suppose where the rumor is from.
Ancient - The same is virus.