Everyone loves Chocobos, Well everyone who loves Final Fantasy, loves Chocobos. They have been available in most Final Fantasy games and in Final Fantasy VII you get the opportunity to breed them, well you have to breed them to obtain the best parts of the game like the Knights Of Round materia. As breeding them can be a hit and miss affair, i thought i would node up a quick guide to the breeds.

Blue Chocobos

This variety can walk on shallow water, like the Tiny Bronco.

While on Disc 2 go back to the Chocobo Stable on the Highwind and rent out all of the stables (6 in all, they are 10000 Gil each). For a start get a Good Chocobo (from the tracks near the Golden Saucer) and a Great Chocobo (from the tracks near Mideel). Breed them with a Carub Nut (won or stolen from the Red Dragons on the grass near Bone Village). The result is a Blue Chocobo.

Green Chocobo

This variety can walk over mountains, But not over mountain peaks.

Catch and raise a Good and a Great Chocobo to A-Class in the Chocobo Races at the Golden Saucer. Breed the Good and Great Chocobos (at A-Class) with a Carub Nut, and you will get a Green Chocobo. Important note - to gain stamina back in the race and speed up your walking speed, hold R1+R2+L1+L2 together while running.

Black Chocobo

This variety is like the blue and green varieties rolled into one.

Now raise the Green and Blue Chocobos up to an A-Class at the Chocobo Races at the Golden Saucer. (See above note on stamina.) Breed the Blue and Green (at A-Class) with a Carub Nut. This gives you a Black Chocobo. Important note - the gender of a Chocobo is not decided until you return to the stable and name it. Before naming the Chocobo save your game, so if you don't get the kinds you want you can try naming the Chocobo again, to see if the gender has changed.

Gold Chocobo

This is the ultimate Chocobo, It can walk on all terrain, and or sea.

Now go to the Chocobo tracks on the Northern Continent (near Icicle Inn) and find a Wonderful Chocobo which is opposite in sex to your Black Chocobo (I recommend you do his before deciding the sex of the Black Chocobo as Wonderful Chocobos are quite rare.). When you find one, get the Wonderful and the Black Chocobo up to an A-Class. Then breed them with a Zeio nut (found on the island to the North of the Chocobo Stable, steal them off a goblin in the forest or buy one off the Chocobo sage to the right of the Icicle Inn area with the Highwind!). Well done, you have a Golden Chocobo.

I found a great list of the effects of the greens in the game here Final Fantasy VII, good luck!