So, Patch 2.35 hit today, most notably adding Ixali beast tribe quests and updates to the hunting marks system. Also, it added the ability to grow fruit to feed to your chocobo. This fruit will change the color of your chocobo. I have planted the fruit for darker blue, red, and green. Once some space is available in the garden, I will plant the other 3 fruit too.
EDIT: Well, it looks like you can maybe customize your color by feeding them combinations of fruit. This post from reddit says:
The patch notes show that there's 7 new fruits you can feed your chocobo to change their colors; three that will increase the color by a shade of red, green, or blue, three that will decrease the shade, and one that will return the chocobo to it's default shade. That would suggest that chocobo colors are based on a RGB scale rather than dye, and thus any color is possible.
The patch notes read:
Once fed, a chocobo's plumage will change in six hours (Earth time).
* The chocobo's plumage will change color depending on the fruit it was fed.
* After the chocobo's plumage changes color, feeding it a Han lemon will restore their plumage to their original yellow hue. Unlike other fruits, the chocobo's plumage will change immediately upon inspecting the chocobo stable a second time.
* No change will occur if chocobos are removed from the stable prematurely. It is recommended to feed them during times when the chocobo can be left stabled for extended periods, such as prior to logging out for the day.
That makes it sound like you can only feed a fruit to a chocobo every six hours, so if you want a specific color, you're going to need to feed it multiple fruits over multiple days, without access to your chocobo while the color is changing. No idea yet by how much the color will increase/decrease.
But, by that logic, certain colored chocobo are going to be harder to obtain since they'll require more fruit than others. And "pure" colors (red, green, blue, black, white, etc.) that require the maximum number of fruit in one direction on all three sliders, will be the most difficult.
Pure black and pure white chocobo are likely going to be the most desired. Gardeners, prepare you soil!
Disclaimer: this is all speculation based on patch notes. You might have to sacrifice 20 catgirls to the RNG god to get the color you want for all I know. /end of quote
Hmm, I can't decide now what color I want. Black would be cool, but I could also do something different like purple or something. Decisions, decisions.