I have all of them from the Pokemon X CD. The Season 4 theme is only 49 seconds long though. The season 2 theme is also short. I think there were no full version of that.
I'll start uploading them now. And I'll try find a longer version of the two short ones.
I would totally love that site if it were in English. And not all of the English themes are available on that site. Most of them are either Portuguese or Japanese. Besides, I don't have them all either.
Edit: I uploaded the rest of the collection I had. I don't have the opening themes for movie 6+ and diamond and pearl.