I used to think that, too, until I found this page on the old NiGHTS site that states that "There are five different Ideya, although few people have them all." And yet, in JoD, Owl says that "All Visitors originally possess a total of five different Ideya." I have no idea which statement should be considered the "correct" one.
I think all dreamers have all the Ideya, just not in equal strengths.
Maybe everyone has five Ideya total, but not necessarily one of each type? Maybe that's a part of what makes Claris, Elliot, Helen, and Will so special; they have all five separate types.
I guess it's really open to interpretation. That's a part of what makes me like the NiGHTS series so much; a lot of it is unexplained (or not explained very well) so the players can decide for themselves what to think.
Sorry, that was off-topic, wasn't it?
I choose white!