Chocobos in "Final Fantasy XV" can change their colors, but only if you receive special pears after finishing certain side quests. You can also win these pears from Chocobo races.

According to RPG Site, players must first unlock Chocobos in Chapter 3 of the game. Complete the "Friends of a Feather" quest for Prompto and the "A Behemoth Undertaking" hunt from Wiz at the Wiz Chocobo Post, which will require you to defeat Deadeye the Behemoth at the quest marker.

IGN has revealed that Deadeye is weak to fire attacks and that players can use the oil drums in the area against the Behemoth. Once he is defeated, return to Wiz. You can now rent Chocobos and take part in Chocobo races. Players can use the Chocobo whistle to summon them, and renting a Chocobo costs 50 gil per day.

In the Chocobo races, you can eat certain greens to boost different traits. Curiel greens will temporarily boost galloping speed. Reagan greens will temporarily boost gliding ability, and Sylkis greens will temporarily boost all your Chocobo's abilities.

Win the race against Prompto, which is unlocked after completing the "A Behemoth Undertaking" quest, to receive the Rounsey Medal. The race against Gladio, which is unlocked after winning against Prompto, will reward you with the Destrier Medal.

The first Chocobo Hoops: Grange Gallop race involves various obstacles and is unlocked once you beat Gladio. Winning this Hoops race will reward you with the Short Course Medal. In Chapter 5, you can unlock the race against Ignis after you beat the Grange Gallop Hoops. This will earn you the Corser Medal. 

The Full Field Race has Noctis racing against everyone and can be unlocked by defeating Ignis. The reward for this race is the Fat Chocobo Medal. Chocobo Hoops: Rocky Road will be unlocked once you win the Full Field Race. After you win the Rocky Road Race, you will earn the Long Course Medal.

In Chapter 6, you can also race against Iris when you beat the Rocky Road Hoops course. If you win, you can get the Jockey Medal from an NPC at the Wiz Chocobo Outpost.

Chocobo colors can be changed when you feed them special pears. This video from Random Chievo's will also help you find the pear locations. The Cieldalaes Pear (00:17 in the video) is in the Prompto and Full Field race.

The Xelphatol Pear (01:01) is in the Gladio or Iris race. The Han Pear (02:17) is in the Ignis and Rocky Road race. The Doman Pear (03:05) is in the Prompto or Ignis race, but it must be raining before the pear becomes available.

The Mamook Pear (03:43) can be found at the Chocobo Hoops race, but it must also be raining. The O'Ghomoro Pear (04:13) is either in the Prompto, Ignis, or Full Field race. However, you must be racing at night during 8:30 p.m. to 4 a.m. The Val Pear (05:03) is in the Rocky Road race, and can also be found during a nighttime race from 8:30 p.m. to 4 a.m.