We don't really know how many legendaries there will be in the end - maybe more will be revealed. But as the Info/Rules thread states, we know of Ho-oh and Lugia, Suicune, Entei and Raikou (the three legendary beasts), the RSE legendaries in Groudon, Kyorge and Rayquazza (Groudon in on version, Kyorge in another, need both to get Rayquazza by reports), and the choice of a level 1 Dialga, Palkia or Giratina with a special move, IF you trade over a movie event Arceus to HG/SS.
That's all we know thus far - maybe that'll be the final number as well. At any rate, thread closed.