This will tell you how to breed the ultimate Gold chocobo in easy to follow steps. Using the Gold Chocobo you can get such materia as KOTR(Knights of the Round), Mime, Quadra-Magic, and HP<->MP.
First you MUST have the Highwind and Chocobo Lure Materia. These are absolute essentials for breeding birds.
First head for the Chocobo Ranch near Midigar with at least 4000 Gil. Once there buy some greens and at least one Chocobo stable from the man in the house. I use Tantal Greens, they work well and aren't too expensive.
After purchasing at least five or six greens, head for the area around the Gold Saucer, where you'll find some < shaped chocobo tracks like the ones around the farm. Try to catch 4 chocobos and then head back to the ranch.
After picking up a couple more stables (max=6) head to Chocobo Billy in the barn and ask to Move Chocobo's. He'll then ask which you want to put in your stable. He'll also give a comment about each chocobo. You NEED one where he says "Mmm... This seems like a good chocobo." That's the one you want to put in your stable. Give it a name that fits it's gender so you'll remember. Then buy some more greens. It's also necessary to let the birds you're not using go.
Now head south to Mideel, the island where Cloud was in his coma. You'll also find some tracks there. Catch four more chocobos and return to the Chocobo Ranch.
Once there opt to move chocobo's again. This time he MUST comment "This is a great chocobo." Now move the chocobo into your stable. Here's the catch. The chocobo's gender must be the opposite of your other one. That's why this could take a while. If it isn't just select the default name and then use the releasing chocobo's option on that one.
Okay. First buy and feed each chocobo A LOT of Tantal Greens. At least 30 or so to each. This will improve their four statistics: Speed, Stamina, Intelligence and Attitude. once you've fed them quite a bit, head for the chocobo room at the Gold Saucer.
Once there you'll find Ester standing outside the staffroom. Ask her to race one of your birds. I usually use the short course but it's up to you. Now you get a chance to check out your bird's speed and stamina.My bird's stamina tends to be higher than the competition but my speed lower which is okay.
Now comes the race. You'll need to win at least 3 races with each bird. That'll move 'em up to B class. You can race them higher, but it isn't necessary. If you do you might encounter a racer named Teihoh. Expect his Black chocobo to burn up the course. Then think how cool it'll be when you have a black bird. If you're having trouble winning, go back to the ranch and feed more greens.
Now it's time to breed them. But you need a nut. Not just any nut... A Carob Nut! There are two ways to get this nut. The Easy way-Pay 500 Gp to the lady in the Wonder Square of the GS. The Harder way-Equip the 'Steal' Materia to someone and head for the fields around Bone Villiage on the N. Continent. There you'll encounter two types of enemies. Squirrel things and Big red Valadokoros Monsters. You can steal the Carob nut from the Valadokoros.
Save outside the ranch. This way you can reset if you don't get the right type. Then head in, select breeding and follow Billy's instructions, giving them the carob nut. If you had a Good Male and a Great Female you'll get a Blue Chocobo. Vice Versa gives you a Green Chocobo.
Here's where it gets tedious. You need both a Green and a Blue Chocobo so you'll have to repeat the above process getting the genders from opposite places. I.e.-If you got a male from the GS area you'll need a female from there this time. Also you may have to reset and breed again several times to get the opposite gender of your other special chocobo. And you can ride them if you want. Green ride up mountains. Blue can cross shallow waters and rivers.
Once you have both Green and Blue, you'll need to pump them up with greens and head to the GS to race them. This time both need to be A Class.
You need the same nut, so get another one and breed your Green and Blue to get a Black Chocobo, which can cross both mountains and rivers. Note- to have room for the Black you'll need six stables and to release the bird's you don'tneed anymore,such as the parents of the Green and of the Blue.
Now buy some more greens and go to the chocobo tracks in the vicinity of Icicle Inn. You need to catch four birds and head back.
Billy's comment this time has to be "This...is a wonderful chocobo!" and again it has to be the opposite gender of the Black one.
Now comes the tough part. Either the Wonderful or the Black HAS to race into the S class, past A. The other can be anything but C class.
This time you'll need a new nut, the Zieo nut. This can ONLY be obtained by stealing it from Goblins. The Goblins live in a forest on an island NorthEast of the Chocobo Ranch.
Breed the Wonderful and Black with the Zieo Nut and TADAAA! you should have a Gold Bird. Note that a Gold Bird looks a lot like a yellow bird but it'll kind of glow.
Now you can go anywhere but underwater. NE of the goblin Island is a Volcano tip with a cave that holds KOTR. A little SE of the chocobo ranch is a cave with Quadra magic. North of the Gold Saucer is a cave with HP<->Mp. On an island west of Rocket town is a cave with Mime.
By the way, there is an "easier" way to get a Gold Chocobo. Beat the Ultimate Weapon on disc 3, then beat the Ruby weapon. Trade the Desert Rose Item you'll recieve for beating it to a man in the top floor of the rightmost building in Kalm. He'll give you a Gold Chocobo in exchange for it.
There is also a rumor that breeding two Gold Chocobos with a special nut will produce a Red Chocobo which is slow, but can fly, or a Silver one (see Rumors Page)that can go under water. This is JUST A RUMOR. I personally have not been able to do it but that doesn't mean it can't be done.