3 questions for Pokemon dream radar?

Question

i was looking at bulbapedia's dream radar page and I saw something that caught my eye.
note the bold

pokemon obtainable at start of game
preferred dream orb color: pink
riolu, drifloon, munna, swablu, sigilyph

pokemon obtainable after catching tornadus
preferred dream orb color: green
igglybuff, shuckle

obtainable after catching thundurus
preferred dream orb color: orange
staryu, porygon, ralts, bronzor

obtainable after catching landorus
preferred dream orb color: blue
togepi, smoochum, spiritomb, rotom

again, note the bold
it says preferred dream orb color: so-and-so
so here are my questions..
what do they mean by preferred dream orb color? do you have to get a lot of orbs that color?
why does it matter?
i've only seen pink and green dream orbs. when will I see blue and orange?

Answer 1

It says preferred orb. This means the Pokemon is more likely to appear in the pink/orange/blue orb. U don't have to have plenty orbs of the colours since you can't collect orbs. As you encounter each of the Therian form Pokemon, a new color of orb is unlocked. All after Tornadus, green orbs appear. Orange orbs appear after Thundurus, and blue unlock after Landorus. The orbs themselves transition between the colors, so to get a color, you have to hit the orb when it's that color.

Hope this helped