Hey, maybe not so much in this manner, specially the fighting part, but it made me think that raising a chocobo that will eventually give you some sort of charm (an accessory of God knows what piece, or something for that incredibly sad pouch slot) who's stats change depending on training. Or a simpler system would be to be able to swap chocobo colors/types somewhere and that directly affect the item corresponding to the chocobo. Notice how each method mentioned (starting from odintius) is increasingly boring, but easier to implement. Honestly I'd like something engaging to be implemented sometime this year. No offense.
Hey, could even be linked with the "Materia" system. Wink wink (read out loud).
Are you insane? You must be because insanity and genius go hand in hand. And this is genius.
I'd LOVE to be able to send my chocobo to places to explore automatically (and offscreen), like the Behests in Final Fantasy Crystal Chronicles: My Life as a King, to gather some modest materials.
It would also be incredibly useful and practical, if we could implement it somehow as a messenger between you and your retainers! We could call our chocobo (whistling can be a skill people, stop with the items already) to send and receive 10 or so items from our retainers (or preferably no limit, just a direct window between you and the retainer as if you were just talking to it, because gear sets can get huge), just give it a cooldown, because the birdy's tired (like 30 minutes or something). It would also help with the farming a bit, specially the Disciples of the Land.
If it's weird for your bird to be tired after carrying your luggage to be called again but be ready for mounting instantly, then make it A messenger chocobo or chocobo service you can pay for (upkeep, weekly, much like Mog Lockers in XI or housing in other games) and A mount chocobo. The logic behind this could be mounting birds are stronger while messengers are smarter, if you are splitting. Hell I don't get paid to make up this stuff, I don't know.
Say you are in the middle of the Black Shroud. Started a party with people you just met in an Aetheryte camp pretty deep and you could use a specific role-- Oh damn, you left your gear in a retainer! -- Say you haven't been there. I hexa-dare you.
How do I always end up with a wall of text? This is why I don't post often.