Running a Final Fantasy Tactics / Tactics Advanced-inspired campaign, you've got to have chocobos! These are based off FFT only; there are several other colors but these give a decent variety. Thank you to [MENTION=6776887]Tormyr[/MENTION] for your Monster CR Calculator - I am not sure I understand it completely but it certainly helped a lot. Please let me know if these CRs look accurate! (I feel like red may be a 2, but I'm not sure.) Comments welcome.
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Chocobos are fairly intelligent ostrich-like birds that run on two feet. Wild chocobo tend to travel in herds in open plains like horses. They are notoriously difficult to capture and train, in part due to their intelligence and stubborn nature. They take far more effort to train than horses, even when born in captivity. They're also more expensive to maintain (and typically associated with the wealthy). However, once trained, they are also far more effective, faster, and steadier in battle. When taught they are able to understand a wide range of language - though they can only say 'kweh!' - and tend to be sensitive to insults and praise.
Yellow Chocobo
Large beast, unaligned
AC 13
Hit points 19 (3d10+3)
Speed 60 ft
Str 16 Dex 17 Con 13 Int 4 Wis 13 Cha 10
Skills Athletics +5, Perception +3
Senses passive Perception 13
Languages --
CR 1/2
ChocoDash - If a yellow chocobo is wearing light or no barding and has at most one rider, when it uses the Dash action its base speed is 80 ft. Similarly, a yellow chocobo can travel at a gallop (PHB p.181) up to 8 hours a day before becoming exhausted.
Actions
ChocoCure - A yellow chocobo may use a bonus action on its turn to heal itself for 8 (1d10+3) hit points. It cannot use this ability again until it finishes a short or long rest.
ChocoPeck - melee weapon attack, +5 to hit, reach 5 ft, one target
Hit: 8 (1d10+3) piercing damage
Yellow chocobos are the most common type of chocobo and prized for their speed and range. They also have the ability to shrug off a small amount of damage. Yellow chocobos also have a strange affection for Moogles, and it is much easier for Moogles to train them - perhaps because they treat it more as a partnership than simple ownership.
Black Chocobo
Large beast, unaligned
AC 14
Hit points 49 (9d10)
Speed 60 ft, fly 20 ft
Str 15 Dex 18 Con 11 Int 4 Wis 13 Cha 13
Skills Athletics +4, Perception +3
Senses passive Perception 13
Languages --
CR 1
Weak Flyer - A black chocobo cannot fly if it is wearing medium or heavier barding or has more than one rider. It also cannot hover or gain more than 100 feet in altitude on its own.
Actions
ChocoBall - 2/rest, ranged weapon attack, +6 to hit, range 30/60 ft, one target
Hit: 9 (2d4+4) bludgeoning damage
A black chocobo can swallow up to two small rocks and store them in its gullet, and spit them out later at surprising speed. It typically uses this ability as a defense mechanism. It can only use this ability twice until it takes a short or long rest.
ChocoPeck - melee weapon attack, +6 to hit, reach 5 ft, one target
Hit: 9 (1d10+4) piercing damage
Black chocobos are more rare than yellow, and in mixed groups of wild chocobo they tend to be the leaders of herds of yellow. They are also prized for their abilities as flying mounts. They aren't the best fliers, but combined with their normal speed their flight is best suited to simply avoiding obstacles. They have also developed a defensive mechanism of spitting rocks when threatened, and often do this from the air while escaping to discourage attackers. Black chocobos are even harder to train and get to accept riders than yellow, but once they do, they are formidable mounts.
Red Chocobo
Large beast, unaligned
AC 14
Hit points 84 (13d10+13)
Speed 60 ft
Str 16 Dex 18 Con 13 Int 5 Wis 13 Cha 16
Skills Athletics +5, Perception +3
Damage resistance fire
Senses passive Perception 13
Languages can understand Common but can't speak
CR 3
ChocoJump - Red chocobos double their jumping distances.
Innate Spellcasting - Red chocobos use Charisma (DC 13) and can innately cast the following without material components.
1/day: ChocoMeteor (Melf's Minute Meteors; Elemental Evil Player's Companion, p.20)
Actions
ChocoPeck - melee weapon attack, +6 to hit, reach 5 ft, one target
Hit: 9 (1d10+4) piercing damage
Red chocobos are exceptionally rare and tend to be loners. More intelligent, they can understand language and have the ability to naturally channel small flaming meteors which they can use at great distance against foes. While they cannot fly, they use their wings to assist in jumping. Even more difficult to capture and train than the other types of chocobo, a red chocobo is almost never seen as a mount or in war - although stories tell of ancient battles where fleets of red chocobo cavalry were used to devastating effect.